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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

Background Acute flaccid paralysis (AFP) surveillance is carried out in Argentina in the frame of the Polio Eradication Program. Acute flaccid myelitis (AFM) is a type of AFP and can be detected in the frame of AFP surveillance. Although many case series of AFM associated to enterovirus (EV) were released since 2014 in many countries, there were no notifications of this entity from Argentina until 2016. Methods Descriptive-observational study. AFP cases reported to the National Surveillance System (NSS) between 2016 and 2018 were included. Results From January 1, 2016 to December 31, 2018, 610 cases of AFP in children under 15 years old were registered (207 in 2016, 205 in 2017 and 198 in 2018). In 2016, from epidemiological weeks (EWs) 14 to 28, 23 cases of AFM were notified (median age 36 months; range: 3 months to 13 years). No special clustering was observed, and the number of AFM cases did not correlate with an increase in the annual rate of AFP notifications. Main prodromal were respiratory symptoms in 21 cases (91.3%) and fever in 18 (78.2%). One or two limbs were affected in 65%; in 35% mechanical ventilation was required. More than 90% had sequelae at discharge. Stool (ST), nasopharyngeal aspirate (NPA) and cerebrospinal fluid (CSF) samples were processed at the Regional Reference Laboratory facilities. RT nested PCR was employed. All detections are shown in Table 1. To note, In 12 cases (53%), EV D68 was detected (11, out of 16 NPA and 3, out of 11 ST samples). As for 2017, only one case of AFM was detected. Attempt of viral detection was unsuccessful. In 2018, 3 cases of AFM were detected, one EV C105, one Coxsackie B and one case without viral detection. Conclusion The occurrence of AFM cases in Argentina since 2016 is similar to the findings in other countries. An association with EV D68 is apparent, notwithstanding the finding of other EV, finding that further points to the causal association between EV D68 and AFM. As NPA is the sample of choice for AFM diagnosis, from 2019 the work-out of every case of AFP includes this sample as mandatory when AFM is suspected. Given the severity and the high rate of permanent sequelae, a high sensitivity of the health team must be sustained to keep with adequate surveillance, which allows prompt outbreak detection of other agents that can cause AFP in the last phase of polio eradication. Disclosures All authors: No reported disclosures.

Background Varicella (VZV) is one of the most frequent exanthematic diseases in childhood. In Argentina, around 150,000–180,000 total cases per year 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. The information provided by epidemiological surveillance is essential to evaluate the impact of public health decisions. Our objective was to describe and to compare the epidemiological situation of VZV infections in Argentina in two periods: pre (2010–2014) and post (2016–2017) vaccine introduction in NIS. Methods Descriptive study. We compared cases and incidence rates (R) of VZV per 100,000 population (global and disaggregated by age) reported to the National Health Surveillance System; in pre (Pre-VV) and post-vaccination (Post-VV) periods. Data analysis of 2015 was excluded since it was considered a transition year. Results Vaccination coverage for 2015 was 44.7%; 74.4% in 2016 and 75.5% in 2017. 728,392 cases of VZV were notified (R = 362,1) in Pre-VV period and 176,995 cases in Post-VV (R = 220.6), with a global incidence rate reduction of 39% (IC 95% =38.9–39.6; P < 0.001). Both 12–24 months of age and 2–4 years old groups (Pre-VV R 2,253 and Post-VV R 1,077; Pre-VV R 2,400 and Post-VV R 1,165, respectively) showed the greatest reductions in incidence rates (–52.2% [IC 95% 51.3–53] P

Background Since The vaccination strategy is a three-dose primary series (at two, Active surveillance is important to opportunely detect variations on these trends. Methods Cross-sectional study, including all hospitalized patients with Hib infection since 2012 to May 2017 at Hospital de Niños “Ricardo Gutiérrez” in Buenos Aires, Argentina. Results Twenty previously healthy children were admitted. Male/female ratio 1.8:1. Median age: 12 (range 45 days-114) months; 85% younger than 2 years and 35% younger than 6 months. Nine patients (45%) had complete vaccination schedule, with three or more doses of DTP-Hib-HBV vaccine. Hospitalization Hib infections by year in Table 1. Clinical presentation: meningitis (14/20), pneumonia (6/20) and arthritis (5/20), osteomyelitis (1/20). All patients with meningitis, 25% of pneumonias and 50% of arthritis had positive blood cultures. Hib was isolated from blood in 17/20 cases, cerebrospinal fluid in 7/14, joint fluid in 3/5 and pleural fluid in 2/6. Median WBC: 12,400/mm3 (1,600–42,900) and median C-reactive protein level 111 mg/L (7–358). Median days of hospitalization was 13 (8–40). Nine patients required intensive care, four of them required mechanical ventilation. None patients died. Immunological studies ruled out immunodeficiency in 10 patients, although four continues under study. Conclusion (i) Burden of invasive Hib infections have increased over the last few years in our setting. (ii) Most of patient had adequate immunization schedule for age; (iii) Surveillance studies should be continued to confirm these preliminary results as well as to evaluate possible causes. Disclosures All authors: No reported disclosures.