Interim Effectiveness Estimates of 2024 Southern Hemisphere Influenza Vaccines in Preventing Influenza-Associated Hospitalization — REVELAC-i Network, Five South American Countries, March–July 2024

To reduce influenza-associated morbidity and mortality, countries in South America recommend annual influenza vaccination for persons at high risk for severe influenza illness, including young children, persons with preexisting health conditions, and older adults. Interim estimates of influenza vaccine effectiveness (VE) from Southern Hemisphere countries can provide early information about the protective effects of vaccination and help guide Northern Hemisphere countries in advance of their season. Using data from a multicountry network, investigators estimated interim VE against influenza-associated severe acute respiratory illness (SARI) hospitalization using a test-negative case-control design. During March 13-July 19, 2024, Argentina, Brazil, Chile, Paraguay, and Uruguay identified 11,751 influenza-associated SARI cases; on average, 21.3% of patients were vaccinated against influenza, and the adjusted VE against hospitalization was 34.5%. The adjusted VE against the predominating subtype A(H3N2) was 36.5% and against A(H1N1)pdm09 was 37.1%. These interim VE estimates suggest that although the proportion of hospitalized patients who were vaccinated was modest, vaccination with the Southern Hemisphere influenza vaccine significantly lowered the risk for hospitalization. Northern Hemisphere countries should, therefore, anticipate the need for robust influenza vaccination campaigns and early antiviral treatment to achieve optimal protection against influenza-associated complications.

Authors

Institutions

Publication Details

Journal
MMWR Morbidity and Mortality Weekly Report
Published
2024-10-03
DOI
https://doi.org/10.15585/mmwr.mm7339a1
Citations
13
Primary Topic
Influenza Virus Research Studies
Type
article
Field-Weighted Citation Impact
5.03

Funders

Controls
|||
ALL TIME
JAN
FEB
MAR
APR
MAY
JUN
JUL
AUG
SEP
OCT
article

Interim Effectiveness Estimates of 2024 Southern Hemisphere Influenza Vaccines in Preventing Influenza-Associated Hospitalization — REVELAC-i Network, Five South American Countries, March–July 2024

Marta Von Horoch, Estefanía Benedetti, Jose Eduardo Silvera, Nathalia Katz et al.
13 citations
MMWR Morbidity and Mortality Weekly Report
Influenza Virus Research Studies
5.03
article

Interim Effectiveness Estimates of 2024 Southern Hemisphere Influenza Vaccines in Preventing Influenza-Associated Hospitalization — REVELAC-i Network, Five South American Countries, March–July 2024

Marta Von Horoch, Estefanía Benedetti, Jose Eduardo Silvera, Nathalia Katz, Annette K. Regan, Greice Madeleine Ikeda do Carmo, Natalia Vergara Mallegas, Carla Voto, Francisco José de Paula Júnior, Perrine Marcenac, Cynthia Vázquez, Miriam Teresinha Furlam Prando Livorati, Cynthia Vázquez, María Paz Rojas Mena, Francisco Nogareda, Martha Velandia-González, María Fernanda Olivares Barraza, Juliana Almeida Leite, Héctor Chiparelli, Ana Catarina de Melo Araújo, Daiana Araújo da Silva, Eduardo Azziz‐Baumgartner, Felipe Cotrim de Carvalho, Paula Couto, Rodrigo Fasce Pineda, Daniel Salas, Ashley Fowlkes, Erica E. Zeno, Natalia Goñi, Marc Rondy, Rebecca Kondor, Silvia Battaglia, Marcela Avendaño, Elena Penayo, Karina Griot, Daiana Tritten, Steven Tapia Villacís, Marcela Avendaño Vigueras, Paula Rodríguez Ferrari, Chavely Domínguez, Laura Castro, Patricia Bustos, Carlos Edson Hott, María Del Valle Juárez, Andrea Pontoriero, Maria José Ortega, Jorge Jara, Walquiria Aparecida Ferreira da Almeida, Eduardo Silvera
article en
13 citations

Abstract

To reduce influenza-associated morbidity and mortality, countries in South America recommend annual influenza vaccination for persons at high risk for severe influenza illness, including young children, persons with preexisting health conditions, and older adults. Interim estimates of influenza vaccine effectiveness (VE) from Southern Hemisphere countries can provide early information about the protective effects of vaccination and help guide Northern Hemisphere countries in advance of their season. Using data from a multicountry network, investigators estimated interim VE against influenza-associated severe acute respiratory illness (SARI) hospitalization using a test-negative case-control design. During March 13-July 19, 2024, Argentina, Brazil, Chile, Paraguay, and Uruguay identified 11,751 influenza-associated SARI cases; on average, 21.3% of patients were vaccinated against influenza, and the adjusted VE against hospitalization was 34.5%. The adjusted VE against the predominating subtype A(H3N2) was 36.5% and against A(H1N1)pdm09 was 37.1%. These interim VE estimates suggest that although the proportion of hospitalized patients who were vaccinated was modest, vaccination with the Southern Hemisphere influenza vaccine significantly lowered the risk for hospitalization. Northern Hemisphere countries should, therefore, anticipate the need for robust influenza vaccination campaigns and early antiviral treatment to achieve optimal protection against influenza-associated complications.

MMWR Morbidity and Mortality Weekly ReportVol. 73(39)
Visual Health Information (US)
Moderna, Universidade de São Paulo, Fundação Oswaldo Cruz, Universidade Federal do Paraná, Universidade Estadual Paulista, Centers for Disease Control and Prevention, Pan American Health Organization, National Center for Immunization and Respiratory Diseases
Openalex Percentile: Top 4%
Influenza Virus Research Studies
5.03
DOIOpen Access PDFOpenAlex
AI Navigator

Ask Laika to Summarize, Analyze, and Connect papers live on the map.

Summarize Papers & Methodologies

Extract key findings, datasets, and comparative methods across publications.

Benchmark Rankings & Visual Analytics

Rank top research institutions, authors, funders, topics, and journals by Field-Weighted Citation Impact (FWCI) and paper volume with instant charts.

Connect Distant Disciplines

Bridge topological clusters on the map to find hidden collaborative intersections.