SARS-CoV-2 B.1.1.529 (Omicron) Variant Transmission Within Households-Four US Jurisdictions, November 2021-February 2022

What is already known about this topic? The SARS-CoV-2 B.1.1.529 (Omicron) variant contributed to a surge of SARS-CoV-2 infections in the United States during December 2021-January 2022. What is added by this report? In a study of household transmission in four U.S. jurisdictions, Omicron infection resulted in high transmission among household contacts, particularly among those who lived with index patients who were not vaccinated or who did not take measures to reduce the risk of transmission to household contacts. What are the implications for public health practice? Multicomponent COVID-19 prevention strategies, including up-to- date vaccination, isolation of infected persons, and mask use at home, are important to reduce Omicron transmission in household settings.