For the first time since 2017, the island government on Thursday declared an influenza epidemic after a sustained increase in the number of cases and fatalities.

Health Secretary Carlos Mellado López, chief epidemiologist Melissa Marzán, and chief medical officer Iris Cardona announced this week that the number of flu-related fatalities had risen to 42. As of Thursday morning, there were 903 hospitalisations and 25,900 reported cases in the influenza season, which began in July.

“This epidemic declaration is to alert and inform citizens about the actions we must take. This is not the time to be alarmed, but to prepare to help prevent the increase in the spread of this virus,” Mellado López said. “Health providers are already working on measures to reduce the spread and prevent the virus. Fortunately, we have enough detection tests, vaccines, and treatments required to deal with influenza cases, and they are all accessible and distributed throughout the island.”

The health chief added that there are guidelines for concrete actions to confront the spread of this virus.

The paediatric population between 0 and 19 years old has been the most affected this season, with 13,666 cases reported. Adults ages 20–59 with influenza account for 9,656 reported cases, while 2,578 cases were recorded among older adults. The sustained increase in influenza cases has occurred for 12 consecutive weeks.

Last year’s season (2022-2023) closed with 31,710 cases of influenza, 1,224 hospitalisations, and 15 fatalities. According to the historical summary of influenza seasons, 2016 was the year in which the most cases were recorded, at 53,708. However, in 2015, 25 fatalities were recorded, while in 2018, some 2,407 hospitalisations were recorded, the highest number of reported hospitalisations.

The epidemic declaration is based on a methodology that occurs when the reporting of cases exceeds the alert threshold for at least four consecutive weeks and represents close to 50% of the total cases recorded for the current flu season. In addition, cases must be identified in all health regions of Puerto Rico, and there must be an incidence level higher than 100 cases per 100,000 people, or the monitoring system of the Centres for Disease Control and Prevention must reach a red status, Marzán said.