Impact of COVID-19 Pandemic Interventions on Sudden Unexpected Death in Infancy Incidence in France

Objective: To study the impact of nonpharmaceutical interventions implemented during the COVID-19 pandemic on the monthly incidence of sudden unexpected death in infancy (SUDI) cases overall and those with a viral or bacterial identification.

Study design: We conducted an interrupted time-series analysis using seasonally adjusted Poisson regression models from the French national prospective and multicenter SUDI registry, that included all SUDI cases below the age of 1 year who died from 2016 to 2021 in mainland France.

Results: Of 998 SUDI cases analyzed, 750 were recorded during the prepandemic period (January 2016 through March 2020) and 248 during the NPI period (April 2020 through December 2021). We found a significant seasonal pattern of overall monthly SUDI incidence, with a peak observed periodically from November to February. The monthly SUDI incidence decreased significantly from the prepandemic to NPI periods (adjusted incidence rate ratio 0.83 [95% CI 0.72-0.96]). In particular, the monthly incidence of SUDI cases with a viral or bacterial identification decreased significantly, while no significant difference was found for SUDI cases without a viral or bacterial identification.

Conclusions: Nonpharmaceutical interventions were associated with a significant change in the incidence of SUDI cases with a viral or bacterial identification. Further investigations are needed to analyze the pathophysiologic role of viruses and bacteria in the SUDI.