Impact of varicella vaccination in Argentina: Seroprevalence in children and adults in a pediatric hospital.

BACKGROUND: Varicella is the primary infection caused by varicella-zoster virus (VZV). In Argentina, the varicella vaccine was introduced in the National Immunization Programme in 2015 as a single dose scheduled at 15 months of age. OBJECTIVES: To estimate VZV seroprevalence in a healthy hospital based population before and after vaccine introduction to the NIP. MATERIAL Y METHODS: Cross-sectional, observational, analytic study. Healthy subjects 1-40 years of age were included between June and December 2019 and tested for VZV-antibodies. Results were compared to data from a similar prevaccination study. RESULTS: Out of 599 samples, 11 indeterminate results were excluded, 424 were positive; overall seroprevalence rate was 72.1% (95 %CI = 68,3-75,8%). No differences were observed between pre and post vaccination studies for overall prevalence or between age groups, except for vaccinated children aged 11-15 (p = 0,005). Rates increased in both periods in subjects aged 6 years or older. Primary vaccine failures were 21%; in subjects <5 years 83% seropositive cases had been vaccinated, in >5 year-olds >90% seropositive cases were associated with a history of infection (OR: 10,4; IC95%: 6,4-16,8; p < 0,001) or household contact (OR:4,8; IC95%: 3,1-7,6; p < 0,001). Vaccination protected against disease (OR: 0.25; 95 %CI: 0.09-0.68; p = 0.004). CONCLUSION: seroprevalence was high in all age groups except in unvaccinated 12 to 15-month infants. Seropositivity was due to vaccination in 15 months to 5 year-old children and to infection in older children.

Impact of varicella vaccine on nosocomial outbreaks and management of post exposure prophylaxis following in a paediatric hospital.

INTRODUCTION: In 2015, varicella vaccine was introduced to the National Immunization Programme in a one-dose regimen for infants aged 15 months. The aim of this study was to describe and compare the epidemiologic characteristics, management strategies and costs of varicella outbreaks in Ricardo Gutierrez Children's Hospital (HNRG) from 2000 to 2019, before (PreV period) and after (PostV period) the introduction of the varicella vaccine. METHODS: A retrospective, analytic study of the impact of nosocomial varicella outbreaks at the HNRG, based on active epidemiologic surveillance. We compared nosocomial varicella outbreaks rates (per 10,000 discharges) between PreV and PostV, excluding the intervention year (2015). RESULTS: During PreV, an average of 15.87 (13.91-18.02) outbreaks per year was observed and in PostV 5.5 per year (3.44-8.32). Outbreaks adjusted by all cause discharges showed a reduction of 59.13% (-36.68%, -73.62%) after vaccine introduction. Considering that in PreV the average of susceptible cases per outbreak was 5.0 and in PostV 7.8, with a cost per susceptible of AR$ $6,522 (80.27 USD) PreV and 6,708 PostV the economic impact on the reduction of outbreaks after the introduction of the vaccine, showed an estimated average savings per year of AR$ -252,128 AR$ (-3,103.11 USD). CONCLUSIONS: The number of annual varicella hospital outbreaks at the HNRG decreased significantly after varicella vaccine was introduced to NIP in Argentina with a relevant reduction in terms of costs.

Bordetella pertussis (Bp) disease: Before (2003-2011) and after (2013-2016) maternal immunization strategy in a pediatric hospital.

INTRODUCTION: Whooping cough continues to be a major cause of morbidity and mortality in infants younger than 1 year. In 2012, Argentina introduced Tdap in pregnancy to prevent infant mortality. The aim of this study is to describe the impact of maternal immunization on the hospitalization and mortality rates of confirmed Bordetella pertussis (Bp) cases by comparing pre- and post-Tdap vaccine recommendation periods. MATERIAL AND METHODS: All PCR-confirmed Bp cases from "R. Gutierrez" Children's Hospital identified between December 2003 and December 2016 were included in. Analysis was performed comparing hospitalization rates (per 10,000 discharges) between pre-vaccination (PreV) 2003-2011 and post-vaccination (PostV) 2013-2016 time periods, excluding the intervention year (2012). RESULTS: During the study time frame, there were 1046 suspected Bp cases, of which 337 (32.2%) were confirmed. Three-hundred eight cases were analyzed (excluding year 2012): 237 in PreV and 71 in PostV. In comparison with PreV, PostV cases were older (3 vs 9 months; p < 0.001), and required less hospitalization (86.9% vs 67.6%; p < 0.001). Bp hospitalization rate (HR) decreased (22.3 vs 11.6; p < 0.001). The mortality rate in PreV 5.9% (14 cases); there were not deaths during PostV (p = 0.036). CONCLUSIONS: Confirmed cases were among infants younger than 1 year In PostV, Bp cases were older and there was a significant decrease in the hospitalization rate. There were no fatal cases in our center after the pregnancy Tdap recommendation was implemented.

Influenza virus: 16 years' experience of clinical epidemiologic patterns and associated infection factors in hospitalized children in Argentina.

BACKGROUND: Influenza is an important cause of acute lower respiratory tract infection (aLRTI), hospitalization, and mortality in children. This study aimed to describe the clinical and epidemiologic patterns and infection factors associated with influenza, and compare case features of influenza A and B. METHODS: In a prospective, cross-sectional study, patients admitted for aLRTI, between 2000 and 2015, were tested for respiratory syncytial virus, adenovirus, influenza, or parainfluenza, and confirmed by fluorescent antibody (FA) or real-time polymerase chain reaction (RT-PCR) assay of nasopharyngeal aspirates. RESULTS: Of 14,044 patients, 37.7% (5290) had FA- or RT-PCR-confirmed samples that identified influenza in 2.8% (394/14,044; 91.4% [360] influenza A, 8.6% [34] influenza B) of cases. Influenza frequency followed a seasonal epidemic pattern (May-July, the lowest average temperature months). The median age of cases was 12 months (interquartile range: 6-21 months); 56.1% (221/394) of cases were male. Consolidated pneumonia was the most frequent clinical presentation (56.9%; 224/394). Roughly half (49.7%; 196/394) of all cases had previous respiratory admissions; 9.4% (37/394) were re-admissions; 61.5% (241/392) had comorbidities; 26.2% (102/389) had complications; 7.8% (30/384) had nosocomial infections. The average case fatality rate was 2.1% (8/389). Chronic neurologic disease was significantly higher in influenza B cases compared to influenza A cases (p = 0.030). The independent predictors for influenza were: age ≥6 months, odds ratio (OR): 1.88 (95% confidence interval [CI]: 1.44-2.45); p<0.001; presence of chronic neurologic disease, OR: 1.48 (95% CI: 1.01-2.17); p = 0.041; previous respiratory admissions, OR: 1.71 (95% CI: 1.36-2.14); p<0.001; re-admissions, OR: 1.71 (95% CI: 1.17-2.51); p = 0.006; clinical pneumonia, OR: 1.50 (95% CI: 1.21-1.87); p<0.001; immunodeficiency, OR: 1.87 (95% CI: 1.15-3.05); p = 0.011; cystic fibrosis, OR: 4.42 (95% CI: 1.29-15.14); p = 0.018. CONCLUSION: Influenza showed an epidemic seasonal pattern (May-July), with higher risk in children ≥6 months, or with pneumonia, previous respiratory admissions, or certain comorbidities.

Análisis de oportunidades perdidas y barreras de vacunación en menores de 7 años que visitan los centros de salud en la ciudad de Azul, año 2022 / Analysis of missed opportunities and vaccination barriers in children under 7 years of age who visit health centers in the city of Azul, year 2022

INTRODUCCIÓN La vacunación universal ha sido una de las estrategias más efectivas en Salud Pública para disminuir la mortalidad infantil. Los problemas de accesibilidad, la complejidad de los esquemas actuales, el miedo a los efectos adversos, la falta de conocimiento por parte de los médicos sobre vacunas y las oportunidades pérdidas de vacunación (OPV) se suman en este tiempo a los asociados a medidas extraordinarias tomadas en el contexto de la pandemia por el virus SARS-Cov2. OBJETIVOS Identificar los principales factores del sistema de salud y del individuo asociados OPV que contribuyen en el descenso de coberturas de vacunas del esquema nacional de vacunación en población menores de 7 años de la ciudad de Azul en el contexto de pandemia. MÉTODOS Se utilizaron las encuestas provistas por la Organización mundial de la salud (OMS) para análisis de OPV. Las mismas fueron administradas a la salida de todos los establecimientos de salud que cuentan con vacunatorios a cuidadores de menores de 7 años, y encuestas autoadministradas sobre conocimiento, actitudes y prácticas al personal de salud dedichos centros. Muestra no probabilística. Las OPV se calcularon en base a las libretas de vacunación o sus registros locales de vacunación según el esquema nacional de vacunación. RESULTADOS Se realizaron 184 encuestas a cuidadores de niños menores de 7 años a la salida de establecimientos de primer y segundo nivel de la ciudad de Azul. La proporción de encuestas para el nivel primario de atención fue de 63,04% (IC 55,63-70,03%) y para el nivel secundario 36,96% (IC 29,97-44,37). Del total de elegibles el 15,43% (IC 10,24-21,93) presentaron al menos una OPV. Al indagar el motivo de no vacunación en dicha población el24% (9,36-45,13) se perdió porque no le preguntaron, otro 24% (9,36-45,13) por cuestiones asociadas a la logística del servicio de vacunación. Los 25 niños elegibles no vacunados representaron un total de 59 OPDV, siendo la 4 dosis de Pentavalente el 16,9% de las mismas (IC 9,47-28,46). Se encuestaron 15 de 34 trabajadores de la salud, hallándose en un 66,67% (38,38-88,18) barreras de conocimiento y un 46,67 (21,27-73,41) presentaron barreras de actitud y prácticas. DISCUSIÓN la herramienta de OPV-OMS permitió caracterizar los motivos potenciales de OPV de nuestra ciudad, siendo la pobre coordinación entre las visitas al sistema de salud y la vacunación incompleta durante las visitas al vacunatorio dos puntos a mejorar.