Elsevier

Vaccine

Volume 36, Issue 24, 7 June 2018, Pages 3555-3566
Vaccine

Seasonal influenza vaccine effectiveness against laboratory-confirmed influenza hospitalizations – Latin America, 2013

https://doi.org/10.1016/j.vaccine.2017.06.036Get rights and content
Under a Creative Commons license
open access

Highlights

  • First multicenter program evaluation of influenza vaccine effectiveness in Latin America.

  • Successful integration of influenza surveillance and vaccination platforms.

  • Influenza vaccines provided moderate protection among young children and older adults.

Abstract

Background

Despite widespread utilization of influenza vaccines, effectiveness (VE) has not been routinely measured in Latin America.

Methods

We used a case test-negative control design to estimate trivalent inactivated influenza VE against laboratory-confirmed influenza among hospitalized children aged 6 months-5 years and adults aged ≥60 years which are age-groups targeted for vaccination. We sought persons with severe acute respiratory infections (SARI), hospitalized at 71 sentinel hospitals in Argentina, Brazil, Chile, Colombia, Costa Rica, El Salvador, Honduras, Panama, and Paraguay during January–December 2013. Cases had an influenza virus infection confirmed by real-time reverse transcription PCR (rRT-PCR); controls had a negative rRT-PCR result for influenza viruses. We used a two-stage random effects model to estimate pooled VE per target age-group, adjusting for the month of illness onset, age and preexisting medical conditions.

Results

We identified 2620 SARI patients across sites: 246 influenza cases and 720 influenza-negative controls aged ≤5 years and 448 cases and 1206 controls aged ≥60 years. The most commonly identified subtype among participants (48%) was the influenza A(H1N1)pdm09 virus followed by influenza A(H3N2) (34%) and influenza B (18%) viruses. Among children, the adjusted VE of full vaccination (one dose for previously vaccinated or two if vaccine naïve) against any influenza virus SARI was 47% (95% confidence interval [CI]: 14–71%); VE was 58% (95% CI: 16–79%) against influenza A(H1N1)pdm09, and 65% (95% CI: −9; 89%) against influenza A(H3N2) viruses associated SARI. Crude VE of full vaccination against influenza B viruses associated SARI among children was 3% (95% CI: −150; 63). Among adults aged ≥60 years, adjusted VE against any influenza SARI was 48% (95% CI: 34–60%); VE was 54% (95% CI: 37–69%) against influenza A(H1N1)pdm09, 43% (95% CI: 18–61%) against influenza A(H3N2) and 34% (95% CI: −4; 58%) against B viruses associated SARI.

Conclusion

Influenza vaccine provided moderate protection against severe influenza illness among fully vaccinated young children and older adults, supporting current vaccination strategies.

Keywords

Influenza
Vaccine effectiveness
Influenza vaccines
Children
Adults
International

Cited by (0)

The findings and conclusions in this report are those of the authors and do not necessarily represent the official position of the US Centers for Disease Prevention and Control.

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Viviana Sotomayor-Proschle, Natalia Vergara, Sergio Loayza, Rodrigo Fasce, Fernando Muñoz, Ministry of Health, Chile; Carla Magda S. Domingues, Ernesto Isaac Montenegro Renoiner, Walquíria Aparecida Ferreira de Almeida, Erica Tatiane Da Silva, Ministry of Health, Brazil; Martha Von Horoch, Cynthia Vazquez, Sonia Arza, Silvia Battaglia, Ministry of Health, Paraguay; Carla Vizzotti, Elsa Baumeister, Paula Couto, Alejandra Gaiano, Carlos Giovacchini, Juan Hermann, Julián Antman, Teresa Varela, Nathalia Katz, Ministry of Health, Argentina; Jacqueline Palacios, Ministry of Health, Colombia; Juliana Barbosa, Patricia Salas, National Health Institute, Colombia; Gabriel Camero, Viviana Calderón, FETP Colombia; Guiselle Guzmán Saborío, Fabio Quesada Córdoba, Antonio García Pérez, Costa Rican Social Security Fund; Jenny Lara Araya, Costa Rican Institute of Research and Education in Nutrition and Health; Marcela Hernández DeMezerville, Wilberth Alfaro Bourret, Hospital Nacional de Niños de Costa-Rica; Julio Armero, Miguel Elas, Héctor Ramos, Celina de Lozano, Ministry of Health, El Salvador; Homer Mejía Santos, Ida Berenice Molina, María Luisa Matute, Rudvelinda Rivera, Ministry of Health, Honduras; Itzel Hewitt, Brechla Moreno, Yadira De Molto, Ministry of Health, Panama.