Epidemiological Alert Simultaneous circulation of seasonal influenza and respiratory syncytial virus - 9 January 2026

On 4 December 2025, the Pan American Health Organization/World Health Organization (PAHO/WHO) issued an alert regarding the possibility of early or more intense activity of respiratory viruses during the 2025-26 season, as compared to previous years. In this context, and based on the behavior observed to date, PAHO/WHO recommends that Member States remain vigilant in order to adjust their health service preparedness and organizational plans in anticipation of possible concurrent outbreaks of seasonal influenza and respiratory syncytial virus, which could overload their health care system.