1. Update re: bamlanivimab monotherapy in the setting of SARS-CoV2 variants
The federal government recently shared concerns regarding the use of bamlanivimab monotherapy in regions where the SARS-CoV2 mutation L452R found in B.1.429/B.1.427 lineages (a.k.a. 20C/CAL.20C) is circulating in high numbers. Given these concerns that the clinical activity of bamlanivimab monotherapy is impacted by this variant and therefore may be less effective, the Health and Human Services Office of the Assistant Secretary for Preparedness and Response (HHS/ASPR) has stopped the distribution of this product to California.
Additionally, the FDA has released revised fact sheets for health care providers, which now include information on susceptibility of SARS-CoV2 variants to each of the monoclonal antibody therapies that are available through an EUA for the treatment of COVID-19. The revised fact sheet for bamlanivimab monotherapy can be found here:
Per the revised fact sheet, bamlanivimab monotherapy is unlikely to be active against the B.1.429/B.1.427 variant, which is circulating in relatively high numbers in California. Health care providers should review the Antiviral Resistance Information in Section 15 of this fact sheet for details regarding specific variants and resistance. For more information regarding variants in California, please refer to the Centers for Disease Control and Prevention (CDC) website (
Variant Proportions in the U.S. | CDC) as well as the California Department of Public Health website (
Tracking Variants (ca.gov)).
While HHS/ASPR is working with the CDC, the National Institutes of Health, and the FDA on recommendations for bamlanivimab monotherapy moving forward, the California Department of Public Health recommends facilities and providers stop administering bamlanivimab monotherapy in California. We will continue to update our stakeholders with any new recommendations.
Note that this recommendation only applies to the administration of bamlanivimab monotherapy at this time. The use of the alternative authorized monoclonal antibodies – (1) bamlanivimab plus etesevimab and (2) casirivimab plus imdevimab – that are expected to retain activity against circulating viral variants may reduce the potential risk of treatment failure should a patient be infected with a SARS-CoV-2 viral variant that is resistant to bamlanivimab alone. Antiviral resistance information can be found in the fact sheets for health care providers for these other two authorized monoclonal antibody products. Health care providers should review the Antiviral Resistance Information in Section 15 of these fact sheets for details regarding specific variants and resistance.