Household exposure, demographic and health characteristics associated with SARS-CoV-2 infection in a cohort study in Northern France.

In this cohort study, we aimed to study the risk of SARS-CoV-2 infection and its association with household exposure, as well as demographic and health factors. Between March 2020 and April 2022, we conducted a cohort study among adults and children aged 5 years or more in a town in northern France. Participants were screened repeatedly for post-infection anti-SARS-CoV-2 immunity. Infection dates were inferred in hierarchical order from symptomatic episodes or virological tests, or if unavailable from the timing of other cases in the household or the window of seroconversion. Household exposure to a case of SARS-CoV-2 during the infectious phase was defined as a time-varying exposure. We included 830 participants with a mean follow-up of 453 days (12,353 total person-months), during which we identified 491 infections (incidence rate 39.7 per 1,000 person-months). In adjusted analyses, exposure in the household to an infected individual was associated with an incidence rate ratio (IRR) of 16.48 (95% CI 12.29-22.09), and baseline statin use was associated with a decreased risk of infection (IRR 0.35, 95% CI 0.13-0.89). These results could contribute to the development of additional prophylactic strategies, e.g., post-exposure, for the population at high risk of severe forms of COVID-19.