Factors associated with severity of adverse events following yellow fever vaccination during the biggest outbreak of the disease recorded in Brazil, 2016-2017. / Fatores associados à gravidade dos eventos adversos pós-vacinação contra a febre amarela durante o maior surto da doença registrado no Brasil, 2016-2017.

OBJECTIVE: to analyze characteristics, incidence and factors associated with serious adverse events (SAEs) following yellow fever vaccination during an outbreak of the disease in Brazil (2016-2017). METHODS: this was a case-control study using data from the National Immunization Program Information System (SI-PNI); SAE were considered to be cases, and non-serious adverse events (NSAE) were considered to be controls. RESULTS: we analyzed 135 SAE cases and 1,058 controls; of the 135 SAE, 79 (58.5%) were males and median age was 28 years [09-49]; incidence in January 2017 reached 1.3 case per 100,000 vaccine doses administered; there was statistical association with males (Odds Ratio [OR]=1.73 - 95%CI 1.20;2.48), primary vaccination (OR=1.65 - 95%CI 1.01;2.71), and being 60 years of age or older taking as reference those aged under 5 (OR=4.4; p-value <0.02). CONCLUSION: SAE owing to yellow fever vaccine showed a greater chance of occurring in men, the elderly and primary vaccination.

Fatores associados à gravidade dos eventos adversos pós-vacinação contra a febre amarela durante o maior surto da doença registrado no Brasil, 2016-2017 / Factores asociados a la gravedad de los eventos adversos posvacunación contra la fiebre amarilla durante el mayor brote de la enfermedad registrado en Brasil, 2016-2017 / Factors associated with severity of adverse events following yellow fever vaccination during the biggest outbreak of the disease recorded in Brazil, 2016-2017

Resumo Objetivo: analisar características, incidência e fatores associados aos eventos adversos graves (EAGs) pós-vacinação contra febre amarela durante surto da doença no Brasil (2016-2017). Métodos: estudo de caso-controle, com dados do Sistema de Informações do Programa Nacional de Imunizações (SI-PNI); foram considerados casos os EAGs, e controles os eventos adversos não graves (EANGs). Resultados: foram analisados 135 casos de EAG e 1.058 controles; dos 135 EAGs, 79 (58,5%) eram homens, e a mediana de idade dos casos, 28 anos (intervalo interquartílico: 9-49); a incidência de EAG em janeiro de 2017 chegou a 1,3 caso por 100 mil doses aplicadas; houve associação estatística com o sexo masculino (odds ratio [OR]=1,73; IC95% 1,20;2,48), ser primovacinado (OR=1,65; IC95% 1,01;2,71), e ter idade ≥60 anos, tomando-se por referência os menores de 5 anos (OR=4,4; p-valor <0,02). Conclusão: EAG pela vacina da febre amarela apresentou maior chance de ocorrer em homens, idosos e primovacinados.

Resumen Objetivo: analizar características, incidencia y factores asociados a eventos adversos graves (EAG) posvacunación contra la fiebre amarilla durante brote de la enfermedad en Brasil (2016-2017). Métodos: estudio de caso-control, con datos del Sistema de Informaciones del Programa Nacional de Inmunizaciones (SI-PNI); se consideraron casos los EAG, y controles los eventos adversos no graves (EANG). Resultados: se analizaron 135 casos de EAG y 1.058 controles; de los 135 EAG, 79 (58,5%) eran hombres, con edad promedio de 28 años [rango intercuartílico: 9-49]; la incidência en enero de 2017 llegó a 1,3 caso por 100 mil dosis aplicadas; ocurrió asociación estadística con el sexo masculino (odds ratio [OR]=1,73 - IC95% 1,20;2,48), ser primovacunado (OR=1,65 - IC95% 1,01;2,71), y tener ≥60 años de edad tomando como referencia a los menores de 5 años (OR=4,4; p-valor <0,02). Conclusión: EAG por la vacuna de la fiebre amarilla presentó mayor probabilidad de ocurrir en hombres, ancianos y primovacunados.

Abstract Objective: to analyze characteristics, incidence and factors associated with serious adverse events (SAEs) following yellow fever vaccination during an outbreak of the disease in Brazil (2016-2017). Methods: this was a case-control study using data from the National Immunization Program Information System (SI-PNI); SAE were considered to be cases, and non-serious adverse events (NSAE) were considered to be controls. Results: we analyzed 135 SAE cases and 1,058 controls; of the 135 SAE, 79 (58.5%) were males and median age was 28 years [09-49]; incidence in January 2017 reached 1.3 case per 100,000 vaccine doses administered; there was statistical association with males (Odds Ratio [OR]=1.73 - 95%CI 1.20;2.48), primary vaccination (OR=1.65 - 95%CI 1.01;2.71), and being 60 years of age or older taking as reference those aged under 5 (OR=4.4; p-value <0.02). Conclusion: SAE owing to yellow fever vaccine showed a greater chance of occurring in men, the elderly and primary vaccination.