Abstract
Background: A large increase in mortality from severe acute respiratory infections (SARI) in Brazil in 2025 was mainly driven by influenza A and respiratory syncytial virus (RSV) among children and the aged, but 2026 data remain largely unpublished.
Methods: Secondary data on SARI by age group (<2, 2-4, 5-14, 15-49, 50-64, 65+ years) and virus (Influenza A/B, RSV, SARS-CoV-2, adenovirus, rhinovirus, bocavirus, and metapneumovirus) were retrieved for 35 weeks of 2026. Weekly variations in infection rate (IR) and mortality rate (MR) were described by virus and age group. Case fatality ratio (CFR) and vaccine-preventable deaths from influenza, RSV, and SARS-CoV-2 were analysed by age group. Missing virus classification was estimated by multinomial regression. Poisson-based 95% confidence intervals (CI) were calculated for MR.
Results: Influenza A infections quintupled during February and March, with a mortality peak in April, mainly due to H2N3. RSV and rhinovirus caused more deaths than influenza viruses, especially among young children (<2) and the aged (65+). The former were most frequently infected by RSV and the latter by rhinovirus. For those 50 years or older, influenza B reached a CFR of about 20%, compared with 5-15% for influenza A, metapneumovirus, rhinovirus, and other non-subtyped viruses. The highest vaccine-preventable MRs per 100,000 were 17.23 for the oldest and 8.62 for the youngest. Under ideal conditions, 6418 lives could have been saved, about half among children and adolescents <15 years old.
Conclusions: Vaccine-preventable SARI in Brazil exerted a high toll in fall and winter 2026, mainly due to influenza A, RSV, and rhinovirus. Better vaccine coverage may significantly reduce this toll.