Regional Update, Influenza and Other Respiratory Viruses. Epidemiological Week 19 (22 May 2026)

Regional situation: In EW 19 of 2026, respiratory virus activity in the Region of the Americas deepens the pattern of inter-hemispheric seasonal transition observed in previous weeks, with an increasingly marked divergence between hemispheres. North America, the Caribbean, and Central America are consolidating the end of the 2025-2026 season, with influenza positivity at low levels close to the interseasonal baseline. In contrast, Brazil and the Southern Cone establish themselves as the subregion of greatest epidemiological relevance for this reporting period, intensifying an accelerated upward trend of the start of the austral winter season, led by Argentina. The Andean Subregion maintains a mixed pattern, with an aggregate decline in influenza but divergent trajectories between countries and with RSV cases that continue to rise. The inter-hemispheric predominance of subtypes persists: influenza B, which has characterized the end of the Northern Hemisphere season, and influenza A, mainly A(H3N2), in the subregions of the Southern Hemisphere. Likewise, RSV shows opposite patterns according to hemisphere: declining in North America and rising in the Andean Region and in Brazil and the Southern Cone, consistent with the start of the austral season. SARS-CoV-2 maintains its generalized decline in all subregions, with no sign of resurgence. The burden of SARI and ILI is declining in the Northern Hemisphere, while the indicators are beginning to reflect an increase in the Southern Cone.