Key clinical point: The risk of contracting COVID-19 among nonimmune family members decreases as the number of immune family members increases.
Major finding: An inverse dose-response association was seen between the number of immune members in each family and the risk for incident COVID-19 in nonimmune family members. Families with 1 immune member had a 45%-61% lower risk for COVID-19, whereas families with 4 immune members had a 97% lower risk.
Study details: The data come from an analysis of 1,789,728 individuals from 814,806 families, consisting of 2-5 members each.
Disclosures: Information on funding was not available. The authors declared no competing interests.
Source: Nordström P et al. JAMA Intern Med. 2021 Oct 11. doi: 10.1001/jamainternmed.2021.5814 .