Adagio Therapeutics, Inc. provided an update following external in vitro analyses to evaluate neutralizing activity of ADG20 against the Omicron SARS-CoV-2 variant. The in vitro data generated through both authentic and pseudovirus testing of the Omicron variant show a greater than 300-fold reduction in neutralizing activity of ADG20 against Omicron. Additional analyses are ongoing, and the company plans to engage with regulatory and government agencies to assess the role ADG20 can play for the prevention and treatment of COVID-19, particularly as the industry’s understanding of the epidemiology and impact of Omicron and potential new variants develops. ADG20 is an investigational monoclonal antibody (mAb) product candidate designed to provide broad and potent neutralizing activity against SARS-CoV-2, including variants of concern, for the prevention and treatment of COVID-19 with potential duration of protection for up to one year with a single injection. In previously disclosed in vitro studies, ADG20 retained activity against prior variants of concern including Alpha, Beta, Delta and Gamma. In addition, in vitro data demonstrated retained neutralizing activity of ADG20 against a diverse panel of circulating SARS-CoV-2 variants, including the Lambda, Mu and Delta plus variants. The safety and efficacy of ADG20 have not been established, and ADG20 is not authorized or approved for use in any country. Adagio is currently evaluating ADG20 in global Phase 2/3 clinical trials for both the prevention and treatment of COVID-19. Based on the in vitro findings related to Omicron, Adagio plans to pause patient recruitment in its Phase 2/3 COVID-19 treatment trial at clinical sites in South Africa, where Omicron has emerged as the dominant variant. Adagio is evaluating next steps for its ADG20 program. In vitro analyses were also conducted on ADG10, a second mAb in development, which showed minimal neutralizing activity against the Omicron variant in both authentic and pseudovirus neutralization assays.