evidence: These research groups continue to work at an unprecedented pace, given the unpredictability of emerging SARS-CoV-2 variants. For example, Sanjana and colleagues are developing tests to understand the mechanisms that enable new variants to become more infectious. They showed how one of the first spike protein mutations, D614G, allowed SARS-CoV-2 variants to enter host cells more easily than the original viral strain could. Today, all currently circulating strains of SARS-CoV-2, including Delta and Omicron, carry the D614G mutation. The Sanjana lab is also developing new genome editing tools to explore the interactions between specific human genetic mutations and viral variants.