VYD2311 is a promising candidate for passive immunization against COVID-19 in immunocompromised individuals

For millions of immunocompromised individuals, vaccines may not elicit adequate protection from infections, so alternative strategies for pre-exposure prophylaxis are essential. There is only one non-vaccine product authorized in the U.S. as pre-exposure prophylaxis against COVID-19: the monoclonal antibody pemivibart. We previously showed that pemivibart had lower neutralizing activity in vitro against many recent dominant SARS-CoV-2 variants, such as KP.3.1.1, NB.1.8.1, and LP.8.1.1, than it had against JN.1, which was dominant when the antibody was first authorized. The manufacturer of pemivibart (Invivyd) recently initated clinical testing of a new monoclonal antibody derived from pemivibart, VYD2311, but there are no available studies of the activity of VYD2311 against dominant and emerging SARS-CoV-2 variants. Here, using pseudovirus neutralization assays, we measured the neutralizing activity of laboratory-synthesized VYD2311 and pemivibart against dominant and emerging SARS-CoV-2 variants, including XFG, NB.1.8.1, and the genetically distant BA.3.2.2. We found that VYD2311 potently neutralized all tested variants in vitro , dramatically more so than pemivibart. Combined with interpretation of earlier clinical trials of a parental antibody product, we conclude that VYD2311 is a promising candidate for passive immunoprophylaxis against COVID-19, particularly for those who do not respond well to vaccination.