Emerging variants of SARS-CoV-2 are showing increased transmissibility, and escape from natural immunity, vaccine protection, and monoclonal antibody therapeutics. The Omicron variant contains about 32 mutations within the spike protein, increasing these concerns of immune escape. Many antiviral therapeutics have recently received approval for emergency use by the FDA, which attack both the SARS-CoV-2 RNA-dependent RNA polymerase (RdRp) and the main protease (Mpro). 

A study tested some clinically relevant SARS-CoV-2 antivirals, against many SARS-CoV-2 variants, including the novel Omicron variant, in live-virus antiviral assays and found the potency of nirmatrelvir to be similar across all variants tested, including Omicron, than the SARS-CoV-2/WA1 strain in both Vero-TMPRSS2 and HeLa-ACE2 cells. EIDD-1931 (the active metabolite of molnupiravir) and remdesivir also showed their activity across variants.

The results were found to be harmonious with the relative conservation observed in the SARS-CoV-2 Mpro and RdRp, as compared to the spike protein, across all variants.

Thus nirmatrelvir, molnupiravir, and remdesivir were found to be active against the Delta and Omicron variants, which make up the majority of new clinical infections. 

Source- bioRxiv, 2022. doi: https://doi.org/10.1101/2022.01.17.476685