Mortality associated with influenza and Omicron infections in France and vaccination of healthcare workers in nursing homes

BackgroundDuring the winter of 2022-2023, high rates of all-cause mortality, not seen since April 2020, were recorded in France, with excess all-cause mortality being related to the Omicron and influenza epidemics during that period. Moreover, that period saw a significant increase in the proportion of residents in long-term care facilities among cases of death in the population. Studies have found that increased influenza vaccination coverage in healthcare workers can result in a substantial reduction (up to 20%-30% during the course of select influenza seasons in the pre-pandemic period) in all-cause mortality in residents in nursing homes. MethodsWe applied the previously developed methodology to estimate the contribution of influenza infections to all-cause mortality in France for the 2014-2015 through the 2018-2019 influenza seasons, and the contribution of both SARS-CoV-2 and influenza infections to all-cause mortality between week 33, 2022 through week 12, 2023. ResultsFor the 2014-2015 through the 2018-2019 seasons, influenza was associated with an average of 15654 (95% CI (13013,18340)) deaths, while between week 33, 2022 through week 12, 2023, we estimated 7851 (5213,10463) influenza-associated deaths and 32607 (20794,44496) SARS-CoV-2 associated deaths. The number of SARS-CoV-2-associated deaths during the Omicron epidemic was significantly higher than the number of deaths with COVID-19 listed on the death certificate or the hospitalization record - for example, between weeks 33-52 in 2022, we estimated 23983 (15307,32620) SARS-CoV-2-associated deaths in France, compared with 12811 deaths with COVID-19 listed on the death certificate, and 8639 in-hospital deaths with COVID-19 during the same period. Examination of US mortality data suggests a significant contribution of Omicron infections to mortality for cardiac disease and mental/behavioral disorders with COVID-19 not listed on the death certificate. ConclusionsOur results suggest the need for boosting influenza vaccination coverage in different population groups (including healthcare workers, particularly nurse assistants for whom influenza vaccination coverage rates in France are low), as well as for wider use of influenza antiviral medications in influenza-related respiratory hospitalizations with different diagnoses (including pneumonia). Wider detection and treatment of Omicron infections, particularly in older individuals/persons with underlying health conditions such as cardiac disease and mental/behavioral disorders, and wider use of bivalent COVID-19 boosters would be needed in the event of the recrudescence of Omicron circulation in France.