In a new study, scientists demonstrate that the UK variant to SARS-CoV-2 is neutralized to the same degree as the reference virus (D614G), whereas the South African variant is less sensitive to neutralizing antibodies. To neutralize the South African variant, the antibody concentrations need to be six times higher than for D614G. This difference in sensitivity was also observed in vaccinated individuals; the antibodies in their serum are effective against the UK variant but less so against the South African one.