Europe needs a sustainably funded influenza research and response network

Influenza viruses have caused four pandemics during the last century.1 The 1918 H1N1 pandemic claimed 20–50 million lives, the 1957 H2N2 pandemic and the 1968 H3N2 pandemic claimed 1–4 million lives each, and the 2009 H1N1 pandemic claimed an estimated 280 000 lives.2,3 Influenza mortality remains high during seasonal epidemics, at 290 000–650 000 global deaths every year.4 Influenza A has an extensive animal reservoir and enormous genetic diversity. Consistently, all four pandemics were caused by influenza A viruses containing viral genomes derived, at least in part, from strains circulating in animals. Influenza A viruses have two different spike proteins: haemagglutinin and neuraminidase. So far, 19 haemagglutinin subtypes and 11 neuraminidase subtypes have been detected in animals, with wild waterfowl as main hosts. Coinfection of one host with different influenza viruses and exchange of genomic segments can lead to progeny viruses with altered virulence, escape from human pre-existing immunity, and efficient human-to-human transmission. Such reassorted viruses have a very high potential to cause the next pandemic. It is plausible that the next pandemic will be due to an influenza A subtype, as four of the last six pandemics were caused by influenza A viruses, with HIV-1 and SARS-CoV-2 causing the other two.