The Fundação Oswaldo Cruz (Fiocruz) has issued a warning regarding an early increase in influenza A circulation across Brazil.

This unexpected timing threatens to overwhelm the national health system by increasing the volume of severe respiratory illnesses before hospitals are fully prepared for the seasonal peak.

According to the InfoGripe bulletin, the influenza season normally begins in April. However, data reported up to 17 April 2026 [1] indicates that the virus began circulating several weeks earlier than expected [1]. This shift has placed the majority of Brazilian states on alert, with particularly high activity recorded in the North and Central-West regions [2].

Health officials are monitoring the rise of severe acute respiratory syndrome (SRAG), a critical complication of the flu. Up to 17 April 2026, there were 4,181 reported cases of SRAG [3]. The surge is accompanied by a stark increase in mortality; deaths attributed to the "super flu" in Brazil have risen by 36.9% [4].

Fiocruz said the early circulation of influenza A increases the risk of severe illness and puts significant pressure on healthcare infrastructure. The agency is urging the population to prioritize vaccination and adhere to preventive measures to mitigate the spread.

While influenza A is the primary concern, officials also noted a slight increase in COVID-19 cases [2]. The convergence of multiple respiratory viruses during an accelerated season complicates triage and treatment processes in public clinics. Fiocruz said that timely vaccination remains the most effective tool to prevent hospitalization and death during this period.

“The influenza season, normally expected to start in April, began several weeks earlier.”

The premature arrival of the influenza season suggests a shift in viral patterns that may require Brazil to adjust its public health calendar. When respiratory surges occur earlier than predicted, vaccine rollout and hospital staffing may not align with peak demand, potentially increasing the mortality rate among vulnerable populations.