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Background In yellow fever (YF) endemic areas, measles, mumps, and rubella (MMR), and YF vaccines are often co-administered in childhood vaccination schedules. Because these are live vaccines, we assessed potential immune interference that could result from co-administration. Methods We conducted an open-label, randomized non-inferiority trial among healthy 1-year-olds in Misiones Province, Argentina. Children were randomized to one of three groups (1:1:1): Co-administration of MMR and YF vaccines (MMR1YF1), MMR followed by YF vaccine four weeks later (MMR1YF2), or YF followed by MMR vaccine four weeks later (YF1MMR2). Blood samples obtained pre-vaccination and 28 days post-vaccination were tested for immunoglobulin G antibodies against measles, mumps, and rubella, and for YF virus-specific neutralizing antibodies. Non-inferiority in seroconversion was assessed using a -5% non-inferiority margin. Antibody concentrations were compared with Kruskal-Wallis tests. Results Of 851 randomized children, 738 were correctly vaccinated, had ≥ 1 follow-up sample, and were included in the intention-to-treat population. Non-inferior seroconversion was observed for all antigens (measles seroconversion: 97.9% in the MMR1YF1 group versus 96.3% in the MMR1YF2 group, a difference of 1.6% [90% CI -1.5, 4.7]; rubella: 97.9% MMR1YF1 versus 94.7% MMR1YF2, a difference of 3.3% [-0.1, 6.7]; mumps: 96.7% MMR1YF1 versus 97.9% MMR1YF2, a difference of -1.3% [-4.1, 1.5]; and YF: 96.3% MMR1YF1 versus 97.5% YF1MMR2, a difference of -1.2% [-4.2, 1.7]). Rubella antibody concentrations and YF titers were significantly lower following co-administration; measles and mumps concentrations were not impacted. Conclusion Effective seroconversion was achieved and was not impacted by the co-administration, although antibody levels for two antigens were lower. The impact of lower antibody levels needs to be weighed against missed opportunities for vaccination to determine optimal timing for MMR and YF vaccine administration. Trial Registration The study was retrospectively registered in ClinicalTrials.gov (NCT03368495) on 11/12/2017.

Introduction Influenza surveillance in Argentina reported influenza-like illness at a rate of 3500/100,000, a hospitalization rate of 15.5/100,000, and a death rate of 0.32/100,000 annually in adults aged over 65 years. The high burden of disease may be due to a combination of immunosenescence and the suboptimal clinical effectiveness of conventional, non-adjuvanted influenza vaccines in this age group. There is a clinical need for more effective influenza vaccines in this population. This study evaluated the cost-effectiveness of an MF59®-adjuvanted trivalent influenza vaccine (aTIV) in adults aged over 65 years in Argentina compared with the non-adjuvanted trivalent influenza vaccine (TIV) used under the current national vaccination policy. Methods A decision tree cost-effectiveness model was developed to estimate the cost-effectiveness of switching from TIV to aTIV in Argentinian older adults. The model compared cost and health benefits of vaccination in one influenza season from the payer perspective. The main predictions included survival, quality-adjusted survival, and costs. Model inputs were sourced from Argentina or internationally where local data was considered inaccurate. Vaccine efficacy assumptions were extracted from recently published, peer-reviewed scientific literature. Results Switching from TIV to aTIV would result in 170 deaths averted and 1310 incremental quality-adjusted life years (QALYs) gained. The incremental cost-effectiveness ratio per QALY was US $2660.59 from the payer perspective. In all sensitivity analyses, aTIV remained highly cost-effective. The probabilistic sensitivity analyses showed a 95% CI per QALY of US $113.74–7721.67. Conclusion Introducing an adjuvanted influenza vaccine in Argentina is potentially beneficial and cost-effective relative to the currently-used TIV through the reduction of disease burden and utilization of healthcare resources.

Heterologous vaccination against coronavirus disease 2019 (COVID-19) provides a rational strategy to rapidly increase vaccination coverage in many regions of the world. Although data regarding messenger RNA (mRNA) and ChAdOx1 vaccine combinations are available, there is limited information about the combination of these platforms with other vaccines widely used in developing countries, such as BBIBP-CorV and Sputnik V. Here, we assess the immunogenicity and reactogenicity of 15 vaccine combinations in 1,314 participants. We evaluate immunoglobulin G (IgG) anti-spike response and virus neutralizing titers and observe that a number of heterologous vaccine combinations are equivalent or superior to homologous schemes. For all cohorts in this study, the highest antibody response is induced by mRNA-1273 as the second dose. No serious adverse events are detected in any of the schedules analyzed. Our observations provide rational support for the use of different vaccine combinations to achieve wide vaccine coverage in the shortest possible time.

Objective To estimate the effectiveness of a two dose vaccine schedule (mRNA-1273, BNT162b2, and BBIBP-CorV) against SARS-CoV-2 infection and covid-19 related death and short term waning of immunity in children (3-11 years old) and adolescents (12-17 years old) during periods of delta and omicron variant predominance in Argentina. Design Test negative, case-control study. Setting Database of the National Surveillance System and the Nominalized Federal Vaccination Registry of Argentina. Participants 844 460 c hildren and adolescents without previous SARS-CoV-2 infection eligible to receive primary vaccination schedule who were tested for SARS-CoV-2 by polymerase chain reaction or rapid antigen test from September 2021 to April 2022. After matching with their corresponding controls, 139 321 (60.3%) of 231 181 cases remained for analysis. Exposures Two dose mRNA-1273, BNT162b2, and BBIBP-CorV vaccination schedule. Main outcome measures SARS-CoV-2 infection and covid-19 related death. Conditional logistic regression was used to estimate the odds of SARS-CoV-2 infection among two dose vaccinated and unvaccinated participants. Vaccine effectiveness was estimated as (1–odds ratio)×100%. Results Estimated vaccine effectiveness against SARS-CoV-2 infection was 61.2% (95% confidence interval 56.4% to 65.5%) in children and 66.8% (63.9% to 69.5%) in adolescents during the delta dominant period and 15.9% (13.2% to 18.6%) and 26.0% (23.2% to 28.8%), respectively, when omicron was dominant. Vaccine effectiveness declined over time, especially during the omicron period, from 37.6% (34.2% to 40.8%) at 15-30 days after vaccination to 2.0% (1.8% to 5.6%) after ≥60 days in children and from 55.8% (52.4% to 59.0%) to 12.4% (8.6% to 16.1%) in adolescents. Vaccine effectiveness against death related to SARS-CoV-2 infection during omicron predominance was 66.9% (6.4% to 89.8%) in children and 97.6% (81.0% to 99.7%) in adolescents. Conclusions Vaccine effectiveness in preventing mortality remained high in children and adolescents regardless of the circulating variant. Vaccine effectiveness in preventing SARS-CoV-2 infection in the short term after vaccination was lower during omicron predominance and decreasing sharply over time. Trial registration National Registry of Health Research IS003720.

Infants’ universal hepatitis A virus (HAV) single-dose vaccination has been highly effective for controlling HAV infection in Argentina, and in other Latin-American countries that adopted that strategy. Although antibodies wane over time, this has not been associated with HAV outbreaks or breakthrough infections, suggesting a relevant role for memory immunity. This study assessed long term humoral and cellular immune memory response after an average of 12 years follow-up of HAV single-dose vaccination. We selected 81 HAV-single dose vaccinated individuals from a 2015 study, including 54 with protective (PAL) and 27 with unprotective antibody levels (UAL) against HAV. Humoral memory response was assessed by measuring anti-HAV antibody titers at admission in both groups, and 30 days after a booster dose in the UAL group. Flow cytometry analysis of peripheral blood mononuclear cell samples stimulated with HAV antigen was performed in 47/81 individuals (21 with PAL, 26 with UAL) to identify activated CD4 + memory T cells or CD8 + memory T cells. The results showed that 48/52 (92%) individuals from UAL group who completed follow up reached protective levels after booster dose. In the PAL group, anti-HAV Abs waned in 2/27 (7%) individuals lacking seroprotection, while in 25/27 (93%) Abs remained >10 mUI/mL. HAV-specific memory CD4 + T cells were detected in 25/47 (53.2%) subjects while HAV-specific memory CD8 + T cells were observed in 16/47 (34.04%) individuals. HAV-specific memory CD4+ and CD8+ T cell responses were detected in 11/21 (52.4%) and in 9/21 (42.9%) subjects with PAL and in 14/26 (53.8%) and in 7/26 (26.9%) individuals with UAL, showing that the presence of memory T-cells was independent of the level or presence of anti-HAV antibodies. Long-term immunity demonstrated in the present work, including or not antibody persistence, suggests that individuals with waned Ab titers may still be protected and supports the single-dose HAV strategy.

In January, 2021, a vaccination campaign against COVID-19 was initiated with the rAd26-rAd5, ChAdOx1 nCoV-19, and BBIBP-CorV vaccines in Argentina. The objective of this study was to estimate vaccine effectiveness at reducing risk of SARS-CoV-2 infection and COVID-19 deaths in people older than 60 years.In this test-negative, case-control, and retrospective longitudinal study done in Argentina, we evaluated the effectiveness of three vaccines (rAd26-rAd5, ChAdOx1 nCoV-19, and BBIBP-CorV) on SARS-CoV-2 infection and risk of death in people with RT-PCR confirmed COVID-19, using data from the National Surveillance System (SNVS 2.0). All individuals aged 60 years or older reported to SNVS 2.0 as being suspected to have COVID-19 who had disease status confirmed with RT-PCR were included in the study. Unvaccinated individuals could participate in any of the analyses. People with suspected COVID-19 who developed symptoms before the start of the implementation of the vaccination programme for their age group or district were excluded from the study. The odds ratio of SARS-CoV-2 infection was evaluated by logistic regression and the risk of death in individuals with RT-PCR confirmed COVID-19 was evaluated by proportional hazard regression models, adjusted for possible confounders: age at the time of the symptom onset date, sex, district of residence, epidemiological week corresponding to the symptom onset date, and history of COVID-19. The estimation of vaccine effectiveness to prevent death due to COVID-19 was done indirectly by combining infection and death estimates. In addition, we evaluated the effect of the first dose of viral vector vaccines across time.From Jan 31, to Sept 14, 2021, 1 282 928 individuals were included, of whom 687 167 (53·6%) were in the rAd26-rAd5 analysis, 358 431 (27·6%) in the ChAdOx1 nCoV-19 analysis, and 237 330 (18·5%) in the BBIBP-CorV analysis. Vaccine effectiveness after two doses was high for all three vaccines, adjusted odds ratio 0·36 (95% CI 0·35-0·37) for rAd26-rAd5, 0·32 (0·31-0·33) for ChAdOx1 nCoV-19, and 0·56 (0·55-0·58) for BBIBP-CorV. After two doses, the effect on deaths was higher than that on risk of infection: adjusted hazard ratio 0·19 (95% CI 0·18-0·21) for rAd26-rAd5, 0·20 (0·18-0·22) for ChAdOx1 nCoV-19, and 0·27 (0·25-0·29) for BBIBP-CorV. The indirectly estimated effectiveness on deaths was 93·1% (95% CI 92·6-93·5) for rAd26-rAd5, 93·7% (93·2-94·3) for ChAdOx1 nCoV-19, and 85·0% (84·0-86·0) for BBIBP-CorV following two doses. First dose effect of viral vector vaccines remained stable over time.The vaccines used in Argentina showed effectiveness in reducing infection and death by SARS-CoV-2 and COVID-19.None.

Durante los días 15 a 17 de junio se llevó a cabo en la ciudad de Mar del Plata el XVII Congreso de la Socie- dad Argentina de Infectología (SADI) 2017, el evento más importante de la infectología de Argentina y uno de los congresos más importantes de América Latina dentro de su especialidad por su impacto a nivel lo- cal y regional. Desde hace años, la presentación de trabajos libres es parte escencial de la conferencia, permitiendo la di- fusión y jerarquización de las investigaciones y expe- riencias de nuestro país y del exterior. Los trabajos libres se categorizaron para su presenta- ción en presentaciones orales, discusión de poster y poster electrónico. Las presentaciones orales se hicie- ron por categoría, incorporándose este año una sesión especial : “orales destacados”. Se trata de una sesión especial donde se exponen los trabajos de mayor jerar- quía de todas las categorías, ya sea por su mayor califi- cación por el comité revisor, características de diseño, importancia para la salud pública y que ofrecieran, en sí mismos, conclusiones y perspectivas que permitan al receptor recibir un mensaje concreto y concluyente. Para la conferencia se recibieron 532 resúmenes, de los cuales 482 (90,6 %) fueron aceptados. Teniendo en cuenta las categorías, el 23,3 % de los trabajos corres- pondieron a Infecciones generales en adultos; 19,5 % a HIV, otros retrovirus y hepatitis virales; 13,7 % a En- fermedades endémicas y medicina del viajero; 9% a Inmunosuprimidos no HIV; 8,6 % a Diagnóstico micro- biológico; 8,3 % a Infecciones asociadas a cuidados de la salud; 7,7% Infecciones en pediatría; 6,6% a Anti- microbianos y 3 % a Vacunas e inmunología. El 2 % de los trabajos fue presentado en la sesión de orales des- tacados, el 10,7 % en la sesión de oral, el 10,5 % en la de discusión de póster, y los restantes en formato de póster electrónico.

Highlights • HPV16/18 decreased by >93% in vaccinated sexually active Argentine girls. • Detected reduction of HPV31 and 45 would add to the success of immunization. • No genotype replacement was observed. • First HPV vaccination monitoring data reported from a Latin American country.

Patients with autoimmune inflammatory rheumatic diseases (AIRDs) are at increased risk of contracting severe infections and suffering complications, particularly when they are receiving immunomodulating therapy. Vaccination is an important means to prevent many potential infections and thereby reduce the morbidity and mortality associated with AIRD. The purpose of this consensus document is to provide health care professionals with recommendations for the vaccination of AIRD patients who reside in Latin America. The recommendations were developed by an expert committee from the region based on a review of the literature and their clinical experience.The Americas Health Foundation (AHF) used PubMed and EMBASE to identify clinicians and scientists with an academic or hospital affiliation and who had published in the field of adult vaccination and rheumatic diseases since 2010. As a result of this effort, AHF convened an 8-member panel of clinical and scientific experts from Latin America. Both the AHF and panel members conducted a careful literature review to identify relevant publications in the areas of adult vaccination and rheumatology, and the sum of the articles identified was provided to the entire panel. Prior to the conference, panelists were each asked to prepare a written response to a salient issue on the subject, identified by AHF.During the conference, each response was edited by the entire group, through numerous drafts and rounds of discussion until a complete consensus on vaccination recommendations for adult patients with AIRDs was obtained, including 7 key recommendations.

New vaccines designed to prevent diseases endemic in low and middle-income countries (LMICs) are now being introduced without prior record of utilization in countries with robust pharmacovigilance systems. To address this deficit, our objective was to demonstrate feasibility of an international hospital-based network for the assessment of potential epidemiological associations between serious and rare adverse events and vaccines in any setting. This was done through a proof-of-concept evaluation of the risk of immune thrombocytopenic purpura (ITP) and aseptic meningitis (AM) following administration of the first dose of measles-mumps-containing vaccines using the self-controlled risk interval method in the primary analysis. The World Health Organization (WHO) selected 26 sentinel sites (49 hospitals) distributed in 16 countries of the six WHO regions. Incidence rate ratios (IRR) of 5.0 (95% CI: 2.5–9.7) for ITP following first dose of measles-containing vaccinations, and of 10.9 (95% CI: 4.2–27.8) for AM following mumps-containing vaccinations were found. The strain-specific analyses showed significantly elevated ITP risk for measles vaccines containing Schwarz (IRR: 20.7; 95% CI: 2.7–157.6), Edmonston-Zagreb (IRR: 11.1; 95% CI: 1.4–90.3), and Enders’Edmonston (IRR: 8.5; 95% CI: 1.9–38.1) strains. A significantly elevated AM risk for vaccines containing the Leningrad-Zagreb mumps strain (IRR: 10.8; 95% CI: 1.3–87.4) was also found. This proof-of-concept study has shown, for the first time, that an international hospital-based network for the investigation of rare vaccine adverse events, using common standardized procedures and with high participation of LMICs, is feasible, can produce reliable results, and has the potential to characterize differences in risk between vaccine strains. The completion of this network by adding large reference hospitals, particularly from tropical countries, and the systematic WHO-led implementation of this approach, should permit the rapid post-marketing evaluation of safety signals for serious and rare adverse events for new and existing vaccines in all settings, including LMICs. Center for Biologics Evaluation and Research (CBER)-U.S. Food and Drug Administration (FDA) funded this project (Grant number U01 FD004575). GRiP, Global Research in Pediatrics, European Union Seventh framework Programme (FP7/2007-2013) provided additional funding under grant agreement nº 261060.

In 2011, Argentina launched a government-funded national Human papillomavirus (HPV) immunization program incorporating a bivalent HPV vaccine, with a 0-1-6-month schedule, for girls 11 years of age, born after January 2000. Monitoring the changes of HPV infection prevalence among young women has been proposed as an endpoint for early assessment of HPV vaccination programs. However, the data on HPV prevalence at young ages are very limited. The aim of this work was to determine the prevalence of HPV infection and type-specific distribution in sexually active 15-17-year-old non-vaccinated girls. Cervical samples from 1073 adolescents were collected for HPV detection and genotyping using the BSGP5+/GP6+PCR-reverse line blot (RLB) assay. Out of 957 specimens analyzed, 56.3% were positive for any HPV type; 42.2% harbored at least one high-risk HPV (HR-HPV) type and 30.8% low-risk HPV (LR-HPV) types. Multiple and single infections were identified in 36.3% and 20.0% of the samples respectively. The 6 most common HR-HPV types were HPV16 (11.1%), HPV52 (10.8%), HPV56 (8.3%), HPV51 (7.4%), HPV58 (7.3%) and HPV31 (7.1%). The prevalence of HR-HPV-16/18 was 15.2%. In conclusion, results confirm that HPV (particularly HR-types) are very common among sexually active adolescents, and prevalence rises quickly after their sexual debut. Our HPV type-specific prevalence baseline may be used to monitor post-vaccinal longitudinal changes in Argentina.

Background In Argentina, around 150,000-180,000 total Varicella (VZV) cases per year (c/y) are registered; however, underreport exists and some 400,000 cases are estimated to occur annually. Varicella vaccine (VV) was included in the National Immunization Schedule (NIS) in 2015, with a 1-dose schedule administered at 15 months-of-age. We aimed to describe and to compare the epidemiological situation of VZV infections in Argentina in two periods: pre (2010-2014) and post (2016-2018) vaccine introduction in NIS. Global Incidence rates and vaccine coverages Incidence rates (age groups) Methods Before-and-after study comparing cases and incidence rates (100,000) of varicella reported to the National Health Surveillance System between pre-vaccination period (Pre-VV) and post-vaccination (Post-VV), excluding year of intervention (2015) since it was considered a transition year. Epi Info 7 was used for data analysis. Results Vaccination coverage (VC) for 2015 was 44.7%; 74.4% in 2016; 76.8% in 2017 and 81% in 2018 (Figure 1). 728,392 cases of VZV were notified (R=363.1) in Pre-VV period and 222,305 cases in Post-VV (R=180.7), with a global incidence rate reduction of 49% (95%CI= 40.9-56.2; p< 0.001). Both 12-24 months of age and 2-4 years old groups (Pre-VV R=2,253 and Post-VV R=900; Pre-VV R=2,399 and Post-VV R=875, respectively) showed the greatest reductions in incidence rates (-59.3% [95%CI 58.7-60] p< 0.001 and -61.7% [95%CI 61.3-62] p< 0.001). Age groups not affected by vaccination (< 1 year, 5-9 years and 10-14 years) presented minor but significant reductions (-56.4% [95%CI 55.6-57.3] p< 0.001; -35% [95%CI 34.5-35.4] p< 0.001; and -28.6% [95%IC 27.6-29.7] p< 0.001 respectively) (Figure 2). Conclusion A decreasing trend in VZV number of cases and incidence rates was observed, especially in children less than 5 years old, despite suboptimal VC. The reduction of VZV cases in non-vaccinated age groups could be related to a decline in the transmission risk. Improving VC will likely reflect a greater impact on the burden of disease. Disclosures All Authors: No reported disclosures

To measure the effectiveness of pneumococcal conjugated vaccine (PCV13) against Community Acquired Pneumonia (CAP) and invasive pneumococcal disease, 2 years after the vaccine (2+1) was included into the National Immunization Program of Argentina, and to describe variables associated with bacterial pneumonia and hospitalization.This was a prospective, population-based surveillance study of CAP incidence (ambulatory and hospitalized) among children less than 5 years of age in the Department of Concordia (Entre Rios, Argentina) from April 2014 - March 2016. The diagnosis of probable bacterial pneumonia (PBP) was determined following the standardized WHO protocol. Incidence during the post-vaccine introduction period was compared with the results from a previous study that used similar methodology for the pre-PCV13 introduction period from 2002 - 2005.During the study period, 330 patients had a clinical diagnosis of CAP, of which 92 were PBP (6 with pleural effusion). S. pneumoniae was not isolated from any sample. No factors associated with PBP were found in multivariable analysis. The decrease in PBP and pleural effusion was significant in relation to the previous study: 63% (P0.0001) and 80.9% (P0.003), respectively. PCV13 uptake was 97.3% for the 1st dose and 84.8% for the booster dose.PCV13 was effective to reduce incidence of consolidated pneumonia and pleural effusion, among children less than 5 years of age in Concordia, Argentina. Vaccination is a very effective public health strategy for reducing vaccine preventable diseases, with impact on burden of disease and hospitalization.Medir la efectividad de la vacuna antineumocócica conjugada (VNC13)contra la neumonía extrahospitalaria y las enfermedades neumocócicas invasoras, dos años después de que se incorporara la vacuna (2+1) en el Programa Nacional de Vacunación de Argentina, y describir las variables asociadas con la neumonía bacteriana y la hospitalización.Se llevó a cabo un estudio prospectivo de vigilancia poblacional de la incidencia de la neumonía extrahospitalaria (pacientes ambulatorios y hospitalizados) en menores de 5 años en el departamento Concordia (Entre Ríos, Argentina) desde abril del 2014 hasta marzo del 2016. Se determinó el diagnóstico de probable neumonía bacteriana según el protocolo estandarizado de la OMS. Se comparó la incidencia durante el período posterior a la incorporación de la vacuna con los resultados de un estudio anterior en el que se usó una metodología similar para el período previo a la incorporación de la VNC13 entre el 2002 y el 2005.Durante el estudio, 330 pacientes presentaron un diagnóstico clínico de neumonía extrahospitalaria, de los cuales 92 presentaron probable neumonía bacteriana (6 con derrame pleural). No se aisló ninguna muestra delLa VNC13 fue efectiva para reducir la incidencia consolidada de derrame pleural y neumonía en menores de 5 años en Concordia (Argentina). La vacunación es una estrategia de salud pública muy efectiva para reducir las enfermedades prevenibles por vacunación, con repercusión en la carga de enfermedad y la hospitalización.Avaliar a efetividade da vacina pneumocócica conjugada (PCV13) em prevenir pneumonia adquirida na comunidade (PAC) e doença pneumocócica invasiva (DPI) após 2 anos da incorporação da vacina (2 + 1) ao Programa Nacional de Vacinação da Argentina e descrever as variáveis associadas à ocorrência de pneumonia bacteriana e internação hospitalar.Estudo prospectivo de base populacional de vigilância da incidência de PAC (atendimento ambulatorial e em internação hospitalar) em crianças menores de 5 anos de idade realizado no Departamento de Concordia, Entre Rios, na Argentina, de abril de 2014 a março de 2016. O diagnóstico de provável pneumonia bacteriana foi determinado segundo o protocolo padronizado da OMS. A incidência no período pós-introdução da vacina foi comparada aos resultados de um estudo anterior realizado com metodologia semelhante no período pré-introdução da PCV13 de 2002 a 2005.No período de estudo, foi feito o diagnóstico clínico de PAC em 330 pacientes, dos quais 92 foram casos de provável pneumonia bacteriana (6 com derrame pleural). A bactériaA PCV13 foi efetiva em reduzir a incidência de pneumonia com consolidação e derrame pleural em crianças menores de 5 anos em Concordia, na Argentina. A vacinação é uma estratégia de saúde pública muito efetiva para reduzir doenças que podem ser evitadas com vacina, com impacto na morbidade e nas internações hospitalares.

BACKGROUND. In 2011, Argentina experienced its highest pertussis incidence and mortality rates of the last decade; 60% of deaths were among infants aged

Vaccination is one of the most effective strategies for disease prevention. Argentina initiated the transition from child vaccination to family vaccination through the incorporation of an adult schedule. One of the difficulties with this last group is to assess the percentage of use (PU) of the vaccines. With the aim of determining the PU of adult vaccines in Argentina, a vaccination module was included in the National Survey of Risk Factors carried out in 2013 by the National Ministry of Health. The sampling had a stratified multistage design. A total of 32 365 people = 18 year-old were surveyed about the use of four vaccines included in the National Vaccination Calendar: hepatitis B, tetanus, influenza, and pneumococcus. The entire population was surveyed for tetanus and hepatitis B while certain groups at risk were evaluated for influenza and pneumococcus, according to current recommendations. PU varied according to the vaccine analyzed: tetanus 49.8%, hepatitis B 21.7%, influenza 51.6% and pneumococcus 16.2%. The main information sources on adult vaccination were media (television, internet, etc.) followed by health personnel (70.8% and 27.9%, respectively). The survey is a suitable tool to assess the use of vaccines by adults, identify low coverage populations, and to plan and implement strategies to improve coverage.

Every year around fourteen million people globally are infected with human papillomavirus (HPV), the sexually transmitted virus that is the cause of most cervical cancers. A number of vaccines have been developed to protect against HPV, but in many countries, HPV vaccination rates have been low compared with rates for other recommended vaccines. Parental concerns, cost, and lack of information and awareness among both health professionals and parents are cited as important barriers to HPV vaccination. In Argentina the HPV vaccine has been provided to all eleven-year-old girls since 2011 as part of a comprehensive national program to prevent cervical cancer. Coverage increased from negligible levels before 2011 to a national average of 87.9 percent for the first dose, 71.6 percent for the second dose, and 52.2 percent for the third dose in 2013. There was a large variance in HPV vaccine coverage across the country's provinces. This article describes key strategies to overcome barriers to implementation of HPV vaccination and provides recommendations for policy makers.

Timely and effective evaluation of vaccine safety signals for newly developed vaccines introduced in low and middle- income countries (LMICs) is essential. The study tested the development of a global network of hospital-based sentinel sites for vaccine safety signal verification and hypothesis testing. Twenty-six sentinel sites in sixteen countries across all WHO regions participated, and 65% of the sites were from LMIC. We describe the process for the establishment and operationalization of such a network and the lessons learned in conducting a multi-country collaborative initiative. 24 out of the 26 sites successfully contributed data for the global analysis using standardised tools and procedures. Our study successfully confirmed the well-known risk estimates for the outcomes of interest. The main challenges faced by investigators were lack of adequate information in the medical records for case ascertainment and classification, and access to immunization data. The results suggest that sentinel hospitals intending to participate in vaccine safety studies strengthen their systems for discharge diagnosis coding, medical records and linkage to vaccination data. Our study confirms that a multi-country hospital-based network initiative for vaccine safety monitoring is feasible and demonstrates the validity and utility of large collaborative international studies to monitor the safety of new vaccines introduced in LMICs.

Poster: "18th ICID / UMP.721 / High effectiveness of PCV13 Vaccine to Prevent Community-Acquired Pneumonia in Adults over 65" by: "G. D. Lopardo1, C. Vizzotti2, N. Giglio1, E. Raimondo3, D. Fridman1, P. micone1, M. Gonzalez4, D. Stamboulian2; 1BUENOS AIRES/AR, 2Ciudad Autonoma de Buenos Aires/AR, 3General Roca/AR, 4Rio Negro/AR"

Background: In 2013, the Pan American Health Organization established a multi-site, multi-country network to evaluate influenza vaccine effectiveness (VE). We pooled data from five consecutive seasons in five countries to conduct an analysis of southern hemisphere VE against laboratory-confirmed influenza hospitalizations in young children and older adults. Methods: We used a test-negative design to estimate VE against laboratory-confirmed influenza in hospitalized young children (aged 6─24 months) and older adults (aged ≥60 years) in Argentina, Brazil, Chile, Colombia, and Paraguay. Following country-specific influenza surveillance protocol, hospitalized persons with severe acute respiratory infections (SARI) at 48 sentinel hospitals (March 2013–December 2017) were tested for influenza virus infection by rRT-PCR. VE was estimated for young children and older adults using logistic random effects models accounting for cluster (country), adjusting for sex, age (months for children, and age-in-year categories for adults), calendar year, country, preexisting conditions, month of illness onset and prior vaccination as an effect modifier for the analysis in adults. Results: We included 8426 SARI cases (2389 children and 6037 adults) in the VE analyses. Among young children, VE against SARI hospitalization associated with any influenza virus was 43% (95%CI: 33%, 51%) for children who received two doses, but was 20% (95%CI: −16%, 45%) and not statistically significant for those who received one dose in a given season. Among older adults, overall VE against SARI hospitalization associated with any influenza virus was 41% (95%CI: 28%, 52%), 45% (95%CI: 34%, 53%) against A(H3N2), 40% (95%CI: 18%, 56%) against A(H1N1)pdm09, and 20% (95%CI: −40%, 54%) against influenza B viruses. Conclusions: Our results suggest that over the five-year study period, influenza vaccination programs in five South American countries prevented more than one-third of laboratory confirmed influenza-associated hospitalizations in young children receiving the recommended two doses and vaccinated older adults. Keywords: Influenza vaccine effectiveness, Children, Adults, Southern hemisphere, Latin America, Severe acute respiratory infections, Test-negative case-control design, Hospitalizations

As a consequence of YF outbreaks that hit Brazil, Argentina, and Paraguay in 2008-2009, a significant demand for YF vaccination was subsequently observed in Argentina, a country where the usual vaccine recommendations are restricted to provinces that border Brazil, Paraguay, and Bolivia. The goal of this paper is to describe the adverse events following immunization (AEFI) against YF in Argentina during the outbreak in the northeastern province of Misiones, which occurred from January 2008 to January 2009. During this time, a total of nine cases were reported, almost two million doses of vaccine were administered, and a total of 165 AEFI were reported from different provinces. Case study analyses were performed using two AEFI classifications. Forty-nine events were classified as related to the YF vaccine (24 serious and 1 fatal case), and 12 events were classified as inconclusive. As the use of the YF 17D vaccine can be a challenge to health systems of countries with different endemicity patterns, a careful clinical and epidemiological evaluation should be performed before its prescription to minimize serious adverse events.

After a country wide outbreak occurred during 2003-2004, 1 dose of hepatitis A vaccine was introduced into Argentinian regular immunization schedule for all children aged 12 months in June 2005. The aim of this study was to assess the impact of this novel intervention.A longitudinal analysis was done of hepatitis A virus (HAV) infection rates reported to the National Epidemiological Surveillance System from 2000 to 2011. Occurrence of fulminant hepatic failure (FHF) and liver transplantation cases up to 2011 were also assessed. Incidence rates and clinical impact were compared between pre- and postvaccination periods (2000-2002 vs. 2006-2011). Notification rates were also compared by age groups and geographical regions.Since 2006, an abrupt decline was observed in HAV infection rates, as well as in FHF and liver transplantation cases. The mean incidence rate of 7.9/100,000 in the postvaccination period represents a reduction of 88.1% (P0.001) when compared with the prevaccination period. Neither FHF nor liver transplantation due to HAV infection were observed since March 2007. Decline in incidence rates was evident in all geographical regions and all age groups but was higher in the prevaccination most affected areas and in young children. Although an absolute decrease was observed for cases and rates in all age groups, since 2006, a higher proportion of cases was observed in people14 years of age.The single-dose vaccination strategy has been highly effective for controlling HAV infection in all age groups till now in Argentina. Long-term surveillance will be critical to document the sustained success of this unique intervention.

Background: Pertussis disease is a growing concern for developing countries. In Argentina, rates of illness and death peaked in 2011. More than 50% of fatalities due to pertussis occurred in infants younger than two months of age, too young for vaccination. In 2012, the government offered immunization with a vaccine containing Tdap to all pregnant women after 20 weeks of gestation with the intent of reducing morbidity and mortality in young infants. Methods: Maternal acellular pertussis vaccine impact on reducing infant disease burden was estimated based on data from the Argentinean Health Surveillance System. We divided Argentinean states in two groups experiencing high (>50) and low (⩽50) Tdap vaccine coverage and compared these two groups using a Bayesian structural time-series model. Low coverage regions were used as a control group, and the time series were compared before and after the implementation of the Tdap program. Findings: We observed a relative reduction of 51% (95% CI [−67%, −35%]; p = 0.001) in pertussis cases in high coverage states in comparison with the low coverage areas. Analysis of infants between two and six months showed a 44% (95% CI [−66%, −24%]; p = 0.001) reduction in illness. Number of deaths was highest in 2011 with 76 fatalities, for an incidence rate of 2.9 per 100,000. Comparing with 2011, rates decreased by 87% to 10 subjects, or 0.9 per 100,000 in 2013. Interpretation: We show an age-dependent protective effect of maternal Tdap immunization in a developing country for infants younger than six months. Fil: Vizzotti, Carla. Ministerio de Salud de la Nación; Argentina Fil: Juarez, Maria V.. Ministerio de Salud de la Nación; Argentina Fil: Bergel, Eduardo. Fundación para la Investigación en Infectología Infantil; Argentina Fil: Romanin, Viviana. Ministerio de Salud de la Nación; Argentina Fil: Califano, Gloria. Ministerio de Salud de la Nación; Argentina Fil: Sagradini, Sandra. Ministerio de Salud de la Nación; Argentina Fil: Rancaño, Carolina. Ministerio de Salud de la Nación; Argentina Fil: Aquino, Analía. Ministerio de Salud de la Nación; Argentina Fil: Libster, Romina Paula. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Fundación para la Investigación en Infectología Infantil; Argentina. Vanderbilt University; Estados Unidos Fil: Polack, Fernando Pedro. Fundación para la Investigación en Infectología Infantil; Argentina. Vanderbilt University; Estados Unidos Fil: Manzur, Juan. Ministerio de Salud de la Nación; Argentina

Single-dose hepatitis A virus (HAV) vaccination was implemented in all Argentinean children 12 months of age in 2005. Previous studies demonstrated high prevalence of protective antibody response 4 years after single-dose vaccination. This study assessed long-term seroprotection against HAV after vaccination.Children who received 1 dose of HAV vaccine at 1 year of age at least 6 years before enrollment were included at 5 centers in Argentina between 2013 and 2014. Demographic and socioeconomic characteristics were collected through a questionnaire. Blood samples were tested for anti-HAV antibodies. Antibody values ≥10 mIU/mL were considered seroprotective. Logistic regression analysis was performed to evaluate the association between demographic and socioeconomic variables and seroprotection.A total of 1088 children were included, with a median postvaccination interval of 7.7 years (range 6.3-9.2 years). Of these children, 97.4% (95% confidence interval: 96.3%-98.3%) had protective antibodies against HAV. No association between demographic or socioeconomic variables and seroprotection was found. Geometric mean concentration of antibody levels against HAV was 170.5 mUI/mL (95% confidence interval: 163.2-178.2 mUI/mL).Single-dose universal hepatitis A immunization in 1-year-old children resulted in sustained immunologic protection for up to 9 years in Argentina. These findings, along with the low current disease burden, confirm the success of the intervention.

Background In January 2012, Argentine introduced PCV-13 to the National Immunization Program. We performed an epidemiological study in order to describe consolidated pneumonia and pneumococcal disease incidence following PCV-13 routine vaccination. Methods Between April2014-March2016, a population-based surveillance study was carried out in Concordia. Clinical data, vaccination status and digital chest X-rays were recorded from children < 5 years old with pneumonia and pleural effusion. A pediatrician and a radiologist interpreted the images independently. A second reference radiologist arbitrated when discordances occurred. Bacterial etiology was investigated in blood and/or in pleural fluid. Probably bacterial pneumonia (PBP) was determined following WHO protocol. Results were compared with previous data (2002–2005) from the pre-PCV-13 vaccination era. Variables associated to consolidated pneumonia were evaluated by multivariate analysis using logistic regression Results 330 patients under 5 years old with pneumonia were assisted during the study period. Of these, 92 (27.9%-IC95% 23.2–33.1) were classified as PBP. Annual incidence rate, in pre and post vaccination period and impact of vaccination are described in table 1. Incidence of pneumococcal disease could not be estimated as pneumococcal isolation was negative in all cases. Multivariate analysis of post-PCV-13 vaccination era showed that incidence of consolidated pneumonia was significantly higher in hospitalized toddlers than outpatients OR: 2,97 (1,65–5,38). Table 1: PBP incidence (*100.000) by study period. Vaccination impact Final Classification Pre-vacccination period Post vaccination period Impact of vaccination N Population Incidence n Population Incidence Incidence Rate ratio (IC95%) Decrease P value Consolidated pneumonia 387 18.053 714,6 86 15.493 283.9 2.5 (1.8–3.6) 60.2%

Background Due to the significant teratogenicity of rubella virus and the use of a live-attentuated vaccine, pregnancy is a contraindication of receipt of rubella vaccine (RCV). Data collected from several countries that have observed susceptible women who had received RCV during pregnancy documented that no infant with congenital rubella syndrome (CRS) has been born, so the risk is theoretical. As part of the regional initiative to eliminate rubella and CRS in the Americas, one of the key strategies was the vaccination of women of childbearing age. The implementation of mass vaccination campaigns targeting women of childbearing age in Argentina, Brazil, Costa Rica, Ecuador, El Salvador, and Paraguay provided an opportunity to further increase the body of knowledge on the safety of rubella vaccine if an unknowingly pregnant woman is vaccinated in early pregnancy. Methods Using a standard protocol, women who were unknowingly pregnant or become pregnant ≤ 30 days after receiving RCV were evaluated to determine immunity status (eg, susceptible, immune, and unknown) at the time of vaccination. Susceptible pregnant women were observed to determine the outcome of the pregnancy. For pregnancies that resulted in live births, serum samples were obtained from the newborn for rubella immunoglobulin (Ig) M antibody testing. If the newborn's serum sample was IgM positive, the infant was evaluated for manifestations of CRS. Results During the period 2001-2008, 48748253 women of childbearing age were vaccinated in the region of the Americas, 39542253 (81%) of whom were vaccinated in the 6 selected countries. Of these women, 30139 (0.07%) were pregnant or became pregnant ≤1 month after receiving vaccine and were followed up. On the basis of serological evaluation, 2894 (10%) women were classified as susceptible at the time of vaccination; of their pregnancies, 1980 (90%) resulted in a live birth. Sera from 70 (3.5%) of these infants were rubella IgM antibody positive, but none of the infants had features of CRS as a result of rubella vaccination. The maximum theoretical risk for CRS following rubella vaccination of susceptible pregnant women was 0.2%. Conclusions. The results of these studies from 6 select countries provides additional evidence showing an absence of risk of CRS associated with administering rubella vaccine shortly before or during pregnancy.

Objective: Since the 10-valent pneumococcal conjugate vaccine (PCV-10) and 13-valent pneumococcal conjugate vaccine (PCV-13) were recently licensed for use in Argentina, both vaccines were evaluated to estimate the costs, health benefits and cost-effectiveness of adding a PCV to the routine child immunization schedule. Methodology: The integrated TRIVAC vaccine cost-effectiveness model from Pan American Health Organization's ProVac Initiative (Version 1.0.65) was used to assess the health outcomes of 20 successive cohorts from birth to 5 years of age. PCV-10 and PCV-13 were each compared to a scenario assuming no PCV vaccination. A 3 + 1 (three doses + booster) schedule and a vaccination price of US$ 20.75 per dose was assumed in the base case for both vaccines. Results: Introduction of PCV-13 rather than PCV-10 would increase the number of life years gained (LYG) by at least 10%. The number of LYG (and LYG after adjustment for DALY morbidity weights) was 56,882 (64,252) for PCV-10 compared to 65,038 (71,628) for PCV-13. From the health system perspective, the cost per DALY averted was US$ 8973 and US$ 10,948 for PCV-10 and PCV-13 respectively, and US$ 8546 and US$ 10,510 respectively, after incorporating costs saved by households. When PCV13 was compared to PCV10 directly, the additional benefits of PCV-13 was conferred at a cost of US$ 28,147 per DALY averted. Cost-effectiveness was influenced mainly by vaccine price, serotype replacement, pneumonia mortality and discount rate. Conclusion: Routine vaccination against S. pneumoniae in Argentina would be cost-effective with either PCV-10 or PCV-13. PCV-13, with higher coverage of local serotypes, would prevent more cases of pneumonia, invasive pneumococcal disease, sequelae and deaths with a higher number of LYG and DALYs averted, but PCV-10, due its higher impact in the prevention of AOM, would save more costs to the healthcare system. (C) 2011 Elsevier Ltd. All rights reserved.

In Argentina, the National Technical Advisory Group on Immunizations is represented by the National Immunization Commission (CoNaIn), an organization created by the Ministry of Health in 2000. Recently, the Argentine government has decided to prioritize vaccination as a state policy, emphasizing this strategy as a sign of social equity so CoNaIn was restructured to increase its capacity to formulate sound and evidence-based recommendations. The commission shall consist of a group of immunization experts, representatives of scientific societies, the immunization program and the Ministry of Health. Its functions include the formulation of recommendations on the introduction of vaccines into the immunization program. The recommendations are based on technical, programmatic and social criteria. This decision-making process transparent with the support and advice of experts and scientific societies and guided by available evidence decisions help strengthen the Ministry of Health immunization policy generating greater confidence and support from the population and health professionals.

Background Despite the current vaccination program in Argentina for older adults (OA), influenza continues to have severe consequences. Estimates based on Argentinian information surveillance system suggest that influenza-like illness reaches an average rate of 3,570/100,000 annually, a hospitalization rate of 15.5/100,000 and a death rate of 0.32/100,000 in OA aged 65+. The high burden of disease in this population is in part due to immunosenescence and the resulting suboptimal clinical effectiveness of influenza vaccines in this age group. There is an unmet clinical need in those aged 65+ for an influenza vaccine that offers enhanced protection. The objective of this study was to evaluate the cost effectiveness (CE) of the MF59 adjuvanted vaccine (aTIV) in Argentina compared with current vaccination policy with an un-adjuvanted vaccine (TIV). Methods A static decision tree CE model of aTIV was developed to estimate the cost effectiveness compared with TIV vaccine in those aged 65+ in Argentina. The model compares cost and health benefits of vaccination in an influenza season from the payer and the societal perspective. The main outcomes include events, death, LLY, QALYs, and costs. To the extent possible, model inputs were sourced from Argentina; in cases where local data were insufficient, international inputs were utilized. Vaccine efficacy assumptions were extracted from recent literature search. Results Using aTIV instead of TIV resulted in additional 530 deaths averted and 3,980 incremental quality-adjusted life-years (QALYs) gained. The incremental cost-effectiveness ratio (ICER) was US$243 and US$937 per QALY from societal and payer′s perspective respectively. In all univariate sensitivity analyses, aTIV remained highly cost-effective meeting the threshold of one GDP per capita in Argentina. From a societal perspective, the probabilistic sensitivity analyses showed aTIV cost-saving in 30% of the simulations. Conclusion This analysis suggests that vaccinating with aTIV in Argentina would be a highly cost-effective in providing additional health gains while reducing healthcare resources utilization and costs. Disclosures N. Giglio, Sanofi Pasteur: Consultant, Speaker honorarium.

En Argentina no existe información publicada sobre la incidencia de tumores asociados (TAS) y no asociados al sida (TnoAS) en pacientes con infección por HIV. Nuestro objetivo fue establecer la incidencia de estos tumores en un centro de atención ambulatoria entre 1997 y 2005. Se reconocieron 103 tumores malignos, de los cuales 73 eran TAS y 30 TnoAS. No hubo diferencias en edad, distribución por sexo y porcentaje de pacientes bajo tratamiento antirretroviral de gran eficacia (TARGA) en ambos grupos. Entre los pacientes con TAS fue más frecuente el diagnóstico simultáneo de tumor e infección HIV (p In Argentina there are no published data on the incidence of AIDS (ARM) and non-AIDS related malignancies (non-ARM) in the HIV positive population. Our aim was to establish the incidence of these malignancies at an ambulatory care center between 1997 and 2005. We describe 103 cases of malignancies, 73 out of them were ARM and 30 were non-ARM. There were no differences in terms of age, gender and proportion of patients on highly active antiretroviral treatment (HAART). Among those patients with ARM, simultaneous diagnosis of malignancy and HIV infection was more frequently seen (p

The importance of vaccination during pregnancy lies not only in directly protecting vaccinated women, but also by indirectly protecting small infants during the first few months of life. Vaccination against the flu and whooping cough is a priority within the comprehensive care strategy for pregnant women and small infants in Argentina, in the context of transitioning from child vaccination to family vaccination.In 2011, the flu vaccine was included in the National Immunization Schedule (NIS) as mandatory and free of charge, with the aim of decreasing complications and death due to influenza in the at-risk population in Argentina. The national vaccination coverage attained in pregnant women in the past 4 years (2011–2014) has been satisfactory; 88% coverage was attained in the year this program was introduced to the schedule. In the following years, coverage was maintained at greater than 95%. In February 2012, Argentina became the first country in Latin America to have universal vaccination strategy for pregnant women against whooping cough. This recommendation was implemented throughout the country by vaccination with the diphtheria toxoid, tetanus toxoid, and acellular pertussis (Tdap) vaccine starting at 20 weeks of pregnancy, with the aim of decreasing morbimortality due to whooping cough in infants under 6 months of age. The vaccine was incorporated into the NIS in 2014. More than 1,200,000 doses were applied in this period. Both vaccines showed a suitable safety profile and no serious events were reported.Argentina is an example of a middle-income country that has been able to implement a successful strategy for primary prevention through vaccines, making it a health policy.

En el abordaje integral del control y prevención del cáncer cérvico uterino, la incorporación de la vacuna contra el virus papiloma humano es una importante oportunidad para reducir de forma significativa la incidencia y mortalidad por esta enfermedad.

Background In 2012 the 13-valent conjugated pneumococcal vaccine (PCV-13) was introduced in the National Immunization Program. We performed an epidemiological study to describe SPN nasopharyngeal carriage prevalence. Methods Between June to September 2015 it was performed a cross-sectional study among children

Introduction. Pertussis is a challenge for public health. Objectives: To describe pertussis-related morbidity and mortality and immunization coverage for the 2002-2011 period, profile of cases for 2011, and control strategies implemented by the Ministry of Health (MoH) of Argentina. Methods. Descriptive, epidemiological surveillance study. Morbidity data were obtained from the National Health Surveillance System, while mortality data were obtained from the MoH’s Health Statistics and Information Department and official jurisdictional reports. Administrative immunization coverage was used based on the data provided by the MoH’s jurisdictions. The Epi Info software, version 7.1.2, was used for analysis. Results. The number of reported cases of pertussis increased between 2002 and 2011, reaching its peak in 2011: an incidence of 16 x 100 000 inhabitants, and 76 deaths. Most deaths occurred in infants younger than 1 year old. Immunization coverage achieved at a national level with the third dose and the dose

Background Rotavirus is a leading cause of severe diarrhea in children under 5. In Argentina, the most affected regions are the Northeast and Northwest, where hospitalizations and deaths are more frequent. This study estimated the cost-effectiveness of adding either of the two licensed rotavirus vaccines to the routine immunization schedule. Methods The integrated TRIVAC vaccine cost-effectiveness model from the Pan American Health Organization's ProVac Initiative (Version 2.0) was used to assess health benefits, costs savings, life-years gained (LYGs), DALYs averted, and cost/DALY averted of vaccinating 10 successive cohorts, from the health care system and societal perspectives. Two doses of monovalent (RV1) rotavirus vaccine and three doses of pentavalent (RV5) rotavirus vaccine were each compared to a scenario assuming no vaccination. The price/dose was US$ 7.50 and US$ 5.15 for RV1 and RV5, respectively. We ran both a national and sub-national analysis, discounting all costs and benefits 3% annually. Our base case results were compared to a range of alternative univariate and multivariate scenarios. Results The number of LYGs was 5962 and 6440 for RV1 and RV5, respectively. The cost/DALY averted when compared to no vaccination from the health care system and societal perspective was: US$ 3870 and US$ 1802 for RV1, and US$ 2414 and US$ 358 for RV5, respectively. Equivalent figures for the Northeast were US$ 1470 and US$ 636 for RV1, and US$ 913 and US$ 80 for RV5. Therefore, rotavirus vaccination was more cost-effective in the Northeast compared to the whole country; and, in the Northwest, health service's costs saved outweighed the cost of introducing the vaccine. Vaccination with either vaccine compared to no vaccination was highly cost-effective based on WHO guidelines and Argentina's 2011 per capita GDP of US$ 9090. Key variables influencing results were vaccine efficacy, annual loss of efficacy, relative coverage of deaths, vaccine price, and discount rate. Conclusion Compared to no vaccination, routine vaccination against rotavirus in Argentina would be highly cost-effective with either vaccine. Health and economic benefits would be higher in the Northeast and Northwest regions, where the intervention would even be cost-saving.

Background Vaccination against hepatitis A (HA) was carried out only as part of a limited outbreak control strategy in Argentina until June 2005, when universal immunization in infants was introduced into the national immunization calendar. A single-dose strategy was chosen instead of the standard two-dose schedule used elsewhere. This study aimed to estimate preventive, medical, and non-medical costs related to HA and to compare these costs in the periods before and after mass vaccination. Methods A retrospective analysis estimated treatment costs of HA and unspecified hepatitis cases reported to the National Health Surveillance System from 2000 to 2010. Costs related to immunization, fulminant hepatitis (FH), liver transplantation, and death were projected as well. Using a social perspective and a healthcare system perspective, costs in two 5-year periods were compared: 2000–2004 versus 2006–2010. Finally, we evaluated the impact of different discount rates, FH risk, and exclusion of unspecified hepatitis cases in the sensitivity analysis. Results Total HA and unspecified hepatitis cases decreased from 157,871 in 2000–2004 to 17,784 in 2006–2010. Medical and non-medical costs decreased from US$11,811,600 and US$30,118,222 to US$1,252,694 and US$4,995,895 in those periods, respectively. Immunization costs increased from US$6,506,711 to US$40,912,132. Total preventive, medical, and non-medical costs decreased from US$48,436,534 to US$47,160,721, representing a 2.6% reduction in total costs between the two periods. When a healthcare system perspective was considered or unspecified hepatitis cases were excluded, total costs were 130.2% and 30.8% higher in 2006–2010 than in the previous period, respectively. Conclusion After implementation of the universal single-dose vaccination against HA in infants in Argentina, an impressive decline was observed in HA cases, with a decrease in medical and non-medical costs in the first 5 years. The single-dose strategy, which is simpler and less expensive than the standard two-dose scheme, can be a good alternative for future vaccination policies in other countries where HA is endemic.

Introduction. Pertussis is a challenge for public health. Objectives: To describe pertussis-related morbidity and mortality and immunization coverage for the 2002-2011 period, profile of cases for 2011, and control strategies implemented by the Ministry of Health (MoH) of Argentina. Methods. Descriptive, epidemiological surveillance study. Morbidity data were obtained from the National Health Surveillance System, while mortality data were obtained from the MoH's Health Statistics and Information Department and official jurisdictional reports. Administrative immunization coverage was used based on the data provided by the MoH's jurisdictions. The Epi Info software, version 7.1.2, was used for analysis. Results. The number of reported cases of pertussis increased between 2002 and 2011, reaching its peak in 2011: an incidence of 16 × 100 000 inhabitants, and 76 deaths. Most deaths occurred in infants younger than 1 year old. Immunization coverage achieved at a national level with the third dose and the dose administered at the time of starting primary education was >90%, while the coverage achieved with the first booster dose was 80%-90%. In 2011, 2821 confirmed cases were reported (incidence of 7 × 100 000 inhabitants): 84% in infants, Facultad de Ciencias Exactas

Background. Single-dose hepatitis A virus (HAV) vaccination was implemented in all Argentinean children aged 12 months in 2005. Between 2005 and 2011, a dramatic decline was observed in HAV infection rates, fulminant hepatitis, and liver transplantation. This study assessed current viral circulation and estimated protective antibody persistence 4 years after vaccination. Methods. Prevalence of prevaccination anti-HAV antibodies in 12-month-old children was evaluated as an indirect estimation of viral circulation (Group A). Seroprevalence was also measured in 5-year-old children who received 1 dose of HAV vaccine at 1 year of age (Group B). Blood samples were tested for immunoglobulin (Ig)G anti-HAV antibodies (seroprotection =10 mIU/mL). All Group A-positive samples were tested for IgM anti-HAV antibodies to identify recent infections. Logistic regression analysis was done to evaluate associations between demographic and socioeconomic variables and seroprotection. Results. Of 433 children from Group A, 29.5% (95% confidence interval [CI], 25.2–33.8) were positive for IgG anti-HAV antibodies with a geometric mean concentration (GMC) of 6.17 mIU/mL (95% CI, 5.33–7.15 mIU/mL); all IgM anti-HAV were negative. From 1139 in Group B, 93% (95% CI, 91.7–94.6) maintained seroprotection with a GMC of 97.96 mIU/mL (95% CI, 89.21–107.57 mIU/mL). Kindergarten attendance was associated with seroprotection in Group B (odds ratio [OR], 2.0; 95% CI, 1.26–3.3). In contrast, high maternal educational level was associated with a lack of seroprotection in this group (OR, .26; 95% CI, .09–.8). Conclusions. Single-dose, universal hepatitis A immunization in infants resulted in low HAV circulation and persistent immunologic protection up to 4 years in Argentina. Variables associated with presence or absence of seroprotection in vaccinated children could be related to differences in hygiene habits in settings with residual viral circulation.

Background Single-dose Hepatitis A Virus (HAV) vaccination was implemented for all Argentinean children aged 12 months in 2005, instead of the standard two-dose schedule. Previous studies demonstrated a dramatic decline in HAV infection rates, fulminant hepatitis, and liver transplantation along with low viral circulation and high prevalence of protective antibody response 8 years following the intervention. This study assessed long-term seroprotection against HAV after vaccination with this novel scheme. Methods Children who received one dose of HAV vaccine at 1 year of age, at least nine years before enrollment, were included at three centers in Argentina between May 2015 and April 2016. Demographic and socio-economic characteristics of the child, mother and house were collected through a questionnaire after informed consent signature. Blood samples were tested for anti-HAV antibodies. Antibody titers ≥10 mIU/mL were considered seroprotective. Logistic regression analysis was done to evaluate associations between different variables and seroprotection. Results Of 1119 children included, 97.0% lived in urban areas, 92.7% had safe water access and 57.8% had sewers at home. Mean age was 10.7 years, and the mean post-vaccination interval was 9.7 years (Range: 9.0–11.3 years). Of the total, 87.6% had protective antibodies against HAV. Higher seroprotection rates were observed in Santa Fe compared with the global rate (91.9% vs. 87.6%; OR 1.94 (95% CI: 1.27–2.95); P = 0.002). In contrast, lowest rates resulted in San Justo, Buenos Aires (81.4% vs. 87.6% OR 0.45 (95% CI: 0.32–0.65); P Conclusion Single-dose universal hepatitis A immunization in infants resulted in sustained immunologic protection up to 11 years in Argentina. Lower seroprevalence rates in San Justo have no clear reason and were not associated with an increase in HAV cases in that area. These findings, along with the low current disease burden confirm the success of the intervention. Disclosures All authors: No reported disclosures.