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Herpes zoster (HZ) is a common disease in older adults and immunocompromised patients, and is frequently associated with long-term complications that impact quality of life. Fortunately, more than one vaccine against HZ is now available in Mexico. Two expert consensus groups discussed adult vaccination strategies in Mexico, focusing on HZ in older adults and immunocompromised individuals; their insights are reported here. HZ is usually treated inappropriately in Mexico. Late diagnosis and suboptimal management are common, as is a lack of treatment options, particularly for pain, which is often unresponsive to standard painkillers. Improving vaccination rates against HZ in Mexico is therefore important, but several barriers to HZ vaccination exist. It is not included in the national vaccination schedule, where included vaccines usually have higher coverage. Actions to overcome barriers include improving awareness of HZ and vaccine availability, developing and promoting guidelines and recommendations for vaccination, and expanding access and infrastructure for vaccination.

Rotavirus (RV) infection causes acute rotavirus gastroenteritis (RVGE) in infants. Safe and effective RV vaccines are available, of which Mexico has included one in its national immunization program (NIP) since 2007. Health outcome gains, expressed in quality-adjusted life years (QALYs), and cost improvements are important additional factors for the selection of a NIP vaccine. These two factors were analyzed here for Mexico over one year implementing three RV vaccines: 2-dose Rotarix (HRV), versus 3-dose RotaTeq (HBRV), and 3-dose Rotasiil (BRV-PV), presented in a 1-dose or 2-dose vial). HRV would annually result in discounted QALY gains of 263 extra years compared with the other vaccines by averting an extra 24,022 homecare cases, 10,779 medical visits, 392 hospitalizations, and 12 deaths. From a payer's perspective and compared with HRV, BRV-PV 2-dose vial and BRV-PV 1-dose vial would annually result in $13,548,179 and $4,633,957 net savings, respectively, while HBRV would result in $3,403,309 extra costs. The societal perspective may also show savings compared with HRV for BRV-PV 2-dose vial of $4,875,860, while BRV-PV 1-dose vial and HBRV may show extra costs of $4,038,363 and $12,075,629 respectively. HRV and HBRV were both approved in Mexico, with HRV requiring less investment than HBRV with higher QALY gains and cost savings. The HRV vaccine produced those higher health gains due to its earlier protection and greater coverage achieved after its schedule completion with two doses only, providing full protection at four months of age instead of longer periods for the other vaccines.

Introduction: The risk of herpes zoster (HZ) increases with age. In countries with an ageing population such as Mexico, a rise in the risk of HZ and complications is expected. The goal of this study was to provide an updated estimate of the potential burden of HZ and associated complications in Mexico., Methods: A retrospective database study was performed using data from the national surveillance database of the Ministry of Health (Secretaría de Salubridad y Asistencia/Dirección General de Información en Salud). HZ cases and associated complications were identified via the International Classification of Diseases 10th Revision codes. Emergency room (ER) visits, hospitalizations, and deaths were extracted and analyzed by age group and year. The observation period was between 2011 and 2020 for ER visits and hospitalizations and between 2011 and 2019 for deaths. Cumulative incidence per 1000 people and case fatality rate were estimated., Results: During the observation period, 53,030 ER visits, 4172 hospitalizations, and 263 deaths due to HZ were reported nationwide. The cumulative incidence of HZ based on ER visits was 1.04 per 1000 people aged ≥ 50 years but increased in older age groups (1.47 per 1000 people aged ≥ 65 years). The most common complications were neuralgia (10.9%), ocular disease (7.0%), meningoencephalitis (2.9%), and disseminated disease (3.1%). Patients ≥ 65 years accounted for 37% of hospitalizations and 81% of deaths., Conclusion: In Mexico, HZ and its complications impose a considerable burden on the population and the healthcare system. Prospective surveillance studies are required to obtain an accurate picture of the current epidemiology of HZ in Mexico and to estimate the benefits of future vaccination strategies against HZ., (© 2022. The Author(s).)

Invasive meningococcal disease (IMD) is an uncommon but serious and potentially fatal condition mainly affecting children and adolescents. Active surveillance between 2005 and 2016 at Tijuana General Hospital, Mexico, indicated that the incidence of IMD in Tijuana was higher than previously thought, at 2.69 per 100,000 population aged <16 years. The objective of this study was to estimate the economic burden associated with 51 IMD cases in children aged <16 years identified over the 11 years of active surveillance at Tijuana General Hospital, Mexico. Healthcare resource usage for the IMD cases was obtained from the hospital database and combined with unit costs from the hospital purchasing department or national databases to estimate total healthcare costs over a follow-up period of 3 months. Societal costs were represented by the value of lost wages for parents or guardians. All costs were expressed in US$. Over the 11-year study period there were 51 IMD cases, of which 13 (25%) were fatal. The total cost for all 51 cases over the 11-year study period was US$1,054,499 (average per case US$20,676), of which direct healthcare costs comprised US$1,029,948 (average per case US$20,195) and societal costs US$24,551 (average per case US$481). Extrapolated to the population of Tijuana region aged <16 years, the estimated annual economic burden of IMD was US$268,794. The major cost driver was the cost of hospitalization. These data illustrate the significant economic burden associated with IMD in Tijuana, and will be useful in assessing optimal vaccination programs against meningococcal disease in Mexico.

Background: Hepatitis A virus (HAV) infection is a leading cause of viral hepatitis in children, yet the HAV vaccine is not included in the national immunization program (NIP) in Mexico. This study addresses an identified evidence gap of the burden of hepatitis A disease, complications, and associated costs in Mexico by analyzing surveillance and healthcare data. Data review included disease morbidity (incidence and hospitalization), mortality, and healthcare resource utilization costs., Methods: In this observational, retrospective database study, we conducted a systematic screening, extraction, and analysis of outcome data from the national surveillance system in Mexico from January 2000 to December 2019., Results: During the analysis period (2000-2019), the average incidence rate/year of HAV cases was 14.7 (5.4-21.5) per 100,000 inhabitants. Children 1-9 years of age (YoA) had the highest average incidence rate/year with 47.8 (14.7-74.5). The average hospitalization rate/year due to HAV infection was 5.8% (2.9-9.6%). Although the highest burden of HAV continued to be in children (1-9 YoA), an increase in incidence and hospitalizations (with complications) in older age groups (≥ 10-64 YoA) was observed. The annual average fatality rate was estimated to be 0.44% (0.26-0.83%) of which 28.8% of deaths were concentrated in adults ≥ 65 YoA. The total direct costs of medical attention due to HAV and related complications were estimated at $382 million Mexican pesos., Conclusion: The overall results suggest an uptrend in HAV infections in adolescents/adults compared to children in Mexico. Therefore, as the overall incidence risk of HAV infection decreases, the mean age of infection increases. This consequently increases the risk of severity and complications in older age groups, thus increasing the demand for healthcare resources. Our findings provide evidence for including the inactivated HAV vaccine in the Mexican NIP., Competing Interests: I have read the journal’s policy and the authors of this manuscript have the following competing interests: AG-H, MYC-A, AA, and GH-G are employed by the GSK group of companies. MYC-A, AA, and GH-G hold shares from the GSK group of companies. GL-C and GS-G are owners of Estimatio SC and report that this company received support from the GSK group of companies to conduct this study. GS-G is an investigator at the Instituto Nacional de Salud Pública (INSP, Mexico). AG-H, MYC-A, AA, GH-G, GL-C, and GS-G declare no other financial and non-financial relationships and activities. ABG and VM-M declare no financial and non-financial relationships and activities and no conflicts of interest.

A systematic review was conducted in Mexico to consolidate and evaluate evidence after 15 years of rotavirus vaccination, according to the National Immunization Program. Five databases were screened to identify published articles (January 2000-February 2020) with evidence on all clinical and epidemiological endpoints (e.g. immunogenicity, safety, efficacy, impact/effectiveness) of rotavirus vaccination in Mexico. Twenty-two articles were identified (observational studies including health-economic models: 17; randomized controlled trials: 5). Fourteen studies evaluated a human attenuated vaccine (HRV), four studies evaluated both vaccines, and only two evaluated a bovine-human reassortant vaccine, with local efficacy data only for HRV. Local evidence shows vaccines are safe, immunogenic, efficacious, and provide an acceptable risk-benefit profile. The benefits of both vaccines in alleviating the burden of all-cause diarrhea mortality and morbidity are documented in several local post-licensure studies. Findings signify overall benefits of rotavirus vaccination and support the continued use of rotavirus vaccine in Mexico.

Background: Low vaccination rates and under-detection of pertussis infections in adolescents and young adults have an impact on the transmission of pertussis to infants. In this study, the proportion of adolescents and young adults with IgG antibodies against B. pertussis antigens, representing recent infection or vaccination, was estimated in a population-based probabilistic survey in Mexico., Methods: Sera and data from 1,581 subjects, including 1,102 adolescents and 479 young adults (10-19 and 20-25 years old, respectively) randomly selected from Mexico's 2012 National Health and Nutrition Survey, were analyzed. IgG antibodies against pertussis toxin (PT) were measured with the CDC/FDA ELISA. A subset of 234 samples was additionally tested with Bp-IgG PT ELISA kit (EUROIMMUN AG, Lubeck, Germany). Threshold values from corresponding test kits were used to identify recent infection or vaccination., Results: Overall anti-PT IgG seroprevalence was 3.9% (95% CI: 2.3-6.3); 3.1% (95% CI: 1.9-5.0) in adolescents, and 4.9% (95% CI: 2.2-11) in young adults. Seroprevalence did not significantly vary by sex, socioeconomic status, region or rural/urban location. Compared to the CDC/FDA ELISA, the EUROIMMUN test showed a 76% sensitivity and 88% specificity. The weighted estimates represent a considerable burden of recent infection in adolescents and young adults; however, most adolescents and adults were seronegative and, therefore, susceptible to pertussis infection., Conclusion: Since booster vaccination to B. pertussis after toddlerhood is not recommended in the Mexican national policy, anti-PT IgG seropositivity may be reasonably attributed to recent infection. Assessing pertussis seroprevalence requires careful consideration of the diagnostic test threshold interpretation and epidemiological model used., Competing Interests: Declaration of Competing Interest EOB and MYCA are employees of the GSK group of companies and hold shares in the GSK group of companies as part of their employee remuneration. RCA and RDA were employees and disclosed shares of the GSK group of companies during the conduct of the study. EOB, MYCA, RCA and RDA declare no other financial and non-financial relationships and activities. HLG, GEA, MASA, SGC, MLT, LCP, MRM, MOP and CMAA declare no financial and non-financial relationships and activities and no conflicts of interest., (Copyright © 2021. Published by Elsevier Ltd.)

Introduction: Pertussis is a highly contagious infectious disease caused by Bordetella pertussis and a leading cause of infant mortality in Mexico. The Tetanus-diphtheria-acellular pertussis (Tdap) vaccine was recommended in the Mexican Immunisation Programme for pregnant women in 2013. We describe pertussis morbidity and mortality trends in infants ≤2 and ≤12 months of age), before and after maternal Tdap immunisation implementation in Mexico., Methods: An ecological retrospective database study was performed in the Mexican National and Workers Social Security Institutes (IMSS; ISSSTE). Data were collected on confirmed pertussis ambulatory cases, hospitalisations, and deaths, plus vaccination coverage (Tdap; Diphtheria-tetanus-acellular pertussis [DTPa]) and population estimates. Descriptive and regression time-trend analyses were performed for pertussis morbidity and mortality in infants between pre- (2010-2012) and post- (2014-2018) maternal Tdap immunisation periods., Results: Around 1 million infants a year are covered in IMSS/ISSSTE databases. Average full primary infant DTPa vaccine coverage was 71.4%-72.7% nationally. Since 2013, annual maternal Tdap vaccine coverage ranged from 70%-93%. Between 2010-2018, 2,024 pertussis cases, 2,518 hospitalisations and 71 deaths were reported in infants. Among infants 0-2 months old (maternal immunisation target group), there was a significant decrease, post-maternal vaccination, in pertussis incidence (49.9%, p < 0.000), hospitalisation (70.0%, p < 0.000) and mortality (82.4%, p = 0.003). In infants 0-12 months old, pertussis hospitalisations (28.9%, p = 0.000) and mortality (36.2%, p = 0.059) decreased, but incidence increased (61.8%, p = 0.000)., Conclusion: After maternal immunisation was implemented, there was a decreasing trend in incidence, hospitalisation and death due to pertussis in infants 0-2 months old. Increases in incidence reported in 0-12-month-olds are likely due to major changes in diagnosis and reporting introduced during the study period as well as limited vaccination and health coverage in some states. These findings confirm the important contribution of the Tdap maternal immunisation programme in reducing pertussis disease burden, particularly severe disease, among infants in Mexico., Competing Interests: Declaration of Competing Interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: [AGH, MYCA, GHG, and PJ are employed by the GSK group of companies. MYCA and PJ hold shares in the GSK group of companies. GSG reports honoraria from the National Institute of Public Health (INSP), however this study was not developed nor performed at the INSP. GLC has no financial relationships and activities to disclose. All authors declare no non-financial relationships and activities.]., (Copyright © 2021 Christine Vanderlinden, Director, Head Publications, GlaxoSmithKline Biologicals S.A. Published by Elsevier Ltd.. All rights reserved.)

Background: We assessed the safety and immunogenicity of 2 + 1 infant regimens initiated with the 13-valent pneumococcal conjugate vaccine (PCV13) and completed with the pneumococcal non-typeable Haemophilus influenzae protein D-conjugate vaccine (PHiD-CV). Methods: This partially blinded study randomized 6-12-week-old infants to receive two-dose priming and a booster (at ages 2, 4, 12-15 months) with: PCV13 at priming and PHiD-CV at boosting (PPS); PCV13 then PHiD-CV at priming and PHiD-CV at boosting (PSS); or PHiD-CV at priming and boosting (SSS control). All analyses were descriptive, i.e., no statistical significance tests were done. Results: The total vaccinated cohort at priming comprised 294 infants. Grade 3 adverse events were reported after 8.7% (PPS), 11.4% (PSS), and 16.9% (SSS) of primary doses (primary objective). No serious adverse events were considered vaccination-related. For most PHiD-CV serotypes, observed percentages of children reaching antibody concentrations ≥0.2 µg/mL and opsonophagocytic activity (OPA) titers above cutoffs were similar across groups 1 month post-priming and post-booster. Observed geometric mean antibody concentrations and OPA titers were lower for some PHiD-CV serotypes with the mixed regimens than with PHiD-CV only, especially for PSS. However, no tests of statistical significance were performed. Conclusions: Immunogenicity of the two mixed PCV13/PHiD-CV regimens seemed mostly similar to that of a PHiD-CV-only series, although observed antibody GMCs and OPA GMTs for some PHiD-CV serotypes were lower. No safety concerns were raised. The clinical relevance of the observed differences is unknown. Clinical trial registration: ClinicalTrials.gov: NCT01641133.

Worldwide, rotavirus infection has been a leading cause of severe diarrhea morbidity and mortality. Two rotavirus vaccines have been used in the National Immunization Program (NIP) in Mexico; two-dose Rotarix from 2006 to 2011 and three-dose RotaTeq since 2011. This study assessed coverage (receiving at least one dose or full dose series) in eligible infants, compliance (% completing dose series and % completing series on schedule) in eligible infants vaccinated with Rotarix (2010) versus RotaTeq (2012), using Mexican Social Security Institute data nationwide and by regions. In 2010, 80.7% received at least one dose of Rotarix , 75.6% received both doses and 57.0% received both doses on schedule. In 2012, 85.7% received at least one dose of RotaTeq , 61.0% received all three doses and 43.2% received all three doses on schedule. More eligible infants received all doses with Rotarix versus RotaTeq (p < 0.001). Among infants vaccinated with Rotarix versus RotaTeq , 93.7% versus 71.1% completed full series (p < 0.001), and 75.5% versus 70.9% completed full series on schedule (p = 0.105), respectively. The full series coverage and compliance decreased in all regions with RotaTeq compared with Rotarix . In conclusion, rotavirus vaccination has successfully reduced morbidity and mortality in children under 5 years in Mexico. This study found significant differences in full series coverage and compliance among infants and a higher proportion of completed scheduled at an earlier age in Mexico when comparing a two-dose vaccine in 2010 with a three-dose vaccine in 2012. Such differences might need to be taken into consideration to maximize NIP benefits, including early protection of the rotavirus vaccination program.

Objectives: To estimate hepatitis B virus (HBV) seroprevalence from natural infection or vaccination in 10-25-year-olds in Mexico, using the 2012 National Health and Nutrition Survey (ENSANUT)., Methods: Randomly selected serum samples (1,581) from adolescents and young adults, representative of 38,924,584 Mexicans, were analyzed to detect hepatitis B surface antigen (HBsAg), hepatitis B surface antibody (anti-HBs) and hepatitis B core antibody (anti-HBc). Weighted HBV seroprevalence in the Mexican population and association with sociodemographic variables were calculated., Results: Overall weighted seroprevalence from natural infection (positive for anti-HBs and anti-HBc) was 0.23% (95% confidence interval [95% CI] 0.10-0.52). No HBsAg was detected, indicating no acute or chronic infection. Vaccine-derived immunity (positive ≥ 10.0 mIU/ml for anti-HBs and negative to anti-HBc) was 44.7% (95% CI: 40.2-49.4) overall; lower in persons aged 20-25 years (40.83%) than in persons aged 10-19 years (47.7%). Among the population analyzed, 54.2% (95% CI: 49.6-58.8) were seronegative to HBV (negative for all three markers) and no sociodemographic risk factors were identified., Conclusions: HBV seroprevalence from natural infection was low. Vaccination-induced immunity was higher among Mexican adolescents than young adults, possibly due to vaccination policies since 1999.

To describe hepatitis A virus (HAV) seroprevalence and associated factors in adolescents (10-19 years) and young adults (20-25 years) in different Mexican regions, using 2012 National Health and Nutrition Survey data. A random selection of 1581 serum samples was analyzed. Weighted HAV seroprevalence with 95% confidence intervals (95%CI) and its association with sociodemographic factors were estimated. Mean weighted HAV seroprevalence was 69.3% (95%CI: 64.8-73.4) overall, with 58.8% (95%CI: 53.4-64.1) in adolescents and 83.0% (95%CI: 75.3-88.7) in young adults. By age of 10, 46.7% (95%CI: 33.9-60.0) were seropositive and by age of 15, 52.8% (95%CI: 36.5-68.5), corresponding to intermediate endemicity nationally. Factors associated with HAV seropositivity (adjusted odds ratio, aOR) included: lower socioeconomic status (SES) (aOR = 4.09 for low and aOR = 2.31 for medium versus high SES), older age (aOR = 0.29 for adolescents versus young adults), living in the South (aOR = 2.12 versus Central Mexico) or in rural areas (aOR = 2.25 versus urban areas). Regional differences and increased seroprevalence of HAV in marginalized populations present an important public health issue, as a relatively large proportion of young adults are susceptible to infection. The burden of symptomatic disease must be addressed further to support specific programs of continued sanitation and education improvement, and the possibility of vaccination in more susceptible regions., (Copyright © 2018 GlaxoSmithKline Biologicals SA. Published by Elsevier Ltd.. All rights reserved.)

Despite vaccination programs, influenza still represents a significant disease burden in Mexico. We conducted an observational, retrospective analysis to better understand the epidemiological situation of the influenza virus in Mexico. Analysis of the seasonal patterns of influenza A and B were based on the Directorate General of Epidemiology dataset of influenza-like illness(ILI), and severe acute respiratory infection(SARI) that were recorded between January 2010 and December 2013. Our objectives were 1) to describe influenza A and B activity, by age group, and subtype and, 2) to analyze the number of laboratory-confirmed cases presenting with ILI by influenza type, the regional distribution of influenza, and its clinical features. Three periods of influenza activity were captured: August 2010-January 2011, December 2011-March 2012, and October 2012-March 2013. Cases were reported throughout Mexico, with 50.3% (n = 10,320) of cases found in 18-49 year olds. Over the entire capture period, a total of 76,085 ILI/SARI episodes had swab samples analyzed for influenza, 27% were positive. During the same period, influenza A cases were higher in the 18-49 years old, and influenza B cases in both 5-17 and 18-49 age groups. Peak activity occurred in January 2012 (n = 4,159) and December 2012 (n = 348) for influenza A and B respectively. This analysis confirms that influenza is an important respiratory pathogen for children and adults in Mexico despite vaccination recommendations. School-age children and adolescents were more prone to influenza B infection; while younger adults were susceptible to both influenza A and B viruses. Over the seasons, influenza A and B co-circulated.

Objective: To estimate the cost effectiveness associated with the use of pneumococcal conjugated vaccines, Prevenar-13 and Synflorix®, in the Mexican pediatric population., Methods: The cost-effectiveness ratio of instrumenting vaccination programs based upon the use of Prevenar-13 and Synflorix® in the Mexican pediatric population was estimated by using a Markov's simulation model. The robustness of the conclusions reached on cost-effectiveness for both vaccines was assayed through an univariate and probabilistic sensitivity analysis that included all of the parameters considered by the model., Results: Synflorix® was dominant over Prevenar-13 in the cost-utility analysis; the former generated more quality-adjusted life years at a lower cost and with a lower incremental cost-utility ratio. Based on the cost-effective analysis, Prevenar-13 generated more life years gained but at a higher cost. The use of Prevenar-13 originated a higher incremental cost-effectiveness ratio and, therefore, it was not cost-effective as compared with Synflorix®., Conclusions: Even though the simulations for Prevenar-13 and Synflorix® revealed both of them to be cost-effective when used to instrument pediatric vaccination campaigns in Mexico, Synflorix® had a better cost-utility/effectiveness profile. In addition, although Prevenar-13 and Synflorix® produced equivalent health outcomes, the overall analysis predicted that Synflorix® would save 360 million Mexican pesos, as compared with Prevenar-13., (Copyright © 2016 International Society for Pharmacoeconomics and Outcomes Research (ISPOR). Published by Elsevier Inc. All rights reserved.)

Reduced-antigen-content diphtheria-tetanus-acellular pertussis (dTpa) vaccine, Boostrix™, is indicated for booster vaccination of children, adolescents and adults. The original prefilled disposable dTpa syringe presentation was recently replaced by another prefilled-syringe presentation with latex-free tip-caps and plunger-stoppers. 671 healthy adolescents aged 10-15 years who had previously received 5 or 6 previous DT(P)/dT(pa) vaccine doses, were randomized (1:1) to receive dTpa booster, injected using the new (dTpa-new) or previous syringe (dTpa-previous) presentations. Immunogenicity was assessed before and 1-month post-booster vaccination; safety/reactogenicity were assessed during 31-days post-vaccination. Non-inferiority of dTpa-new versus dTpa-previous was demonstrated for all antigens (ULs 95% CIs for GMC ratios ranged between 1.03-1.13). 1-month post-booster, immune responses were in similar ranges for all antigens with both syringe presentations. dTpa delivered using either syringe presentation was well-tolerated. These clinical results complement the technical data and support the use of the new syringe presentation to deliver the dTpa vaccine.