Brazil reports 81% drop in infant RSV cases after vaccine, but severe flu B cases surge in Brasília

The State Health Secretariat of Paraná announced an 81.1% reduction in severe acute respiratory syndrome (SRAG) cases caused by respiratory syncytial virus (RSV) among infants under six months, falling from 1,421 to 269 cases when comparing the first 26 weeks of 2025 with the same period in 2026. The decline follows the inclusion of the RSV vaccine in the national immunisation programme in December 2025 and a high maternal‑vaccination coverage of 89.84% in the state. Paraná also employs the monoclonal antibody nirsevimab for high‑risk newborns. Nationwide, RSV cases dropped 52.9% between 2025 and 2026.

In the Federal District, health officials report a rise in severe influenza B cases, keeping the region on an elevated SRAG alert together with states such as Goiás, Minas Gerais, Rio de Janeiro and Santa Catarina. Influenza B, though less known than influenza A, can lead to serious complications, especially in children, the elderly, pregnant women and people with chronic conditions. Treatment follows standard supportive care, with antivirals like oseltamivir recommended for high‑risk patients within 48 hours of symptom onset. The contrasting trends highlight ongoing challenges in Brazil’s respiratory disease burden despite vaccine successes.