Influenza, over 16 million cases in Italy in the 2024-2025 season

The most recent RespiVirNet surveillance report, issued by the Italian National Institute of Health (ISS) and updated to April 20, 2025, indicated that there were an estimated 16,129,000 cases of influenza-like illness during the 2024-2025 influenza season. This figure represents an increase of approximately 1.5 million cases compared to the previous year. In the final week of the survey period, the proportion of samples yielding positive results for influenza was 3.7% (221,000 cases), a decrease from the preceding week (-5.6%). The European Centre for Disease Prevention and Control (ECDC) has corroborated that the past influenza season was also characterized by heightened intensity within the European Union and the European Economic Area. Giovanni Rezza, Associate Professor of Hygiene at the Vita-Salute San Raffaele University in Milan, has stated that the elevated number of cases is primarily attributable to the co-circulation of multiple viral strains, with approximately one-third of cases caused by influenza A/H1 viruses, one-third by A/H3 viruses, and one-third by influenza viruses of type B, in addition to other respiratory viruses, including rhinovirus and respiratory syncytial virus. The estimates elaborated at the end of April by the Centers for Disease Control and Prevention (CDC) for the United States count between 47 and 82 million people affected by flu syndromes; between 610 thousand and 1.3 million hospitalizations and between 26 thousand and 130 thousand deaths. Among these, at least 216 minors have already been confirmed. These epidemiological numbers have prompted the US to begin trials to develop a universal flu vaccine within 4 years.