On May 26, 2021, given the sustained increase in the P.1 and B.1.351 variants, the Assistant Secretary for Preparedness and Response (ASPR) within the U.S. Department of Health and Human Services (HHS) stopped the distribution of bamlanivimab plus etesevimab to California. The Centers for Disease Control and Prevention (CDC) has identified that the combined frequency of the P.1 variant and the B.1.351 variant now exceeds 10% in California. Results from in vitro assays that are used to assess the susceptibility of viral variants to particular monoclonal antibodies suggest that bamlanivimab and etesevimab administered together are not active against either the P.1 or B.1.351 variants.