Variants vary, but how much? Since SARS-CoV-2 was first sequenced at the beginning of 2020 dozens of strains have been identified. And five have been designated “variants of concern” by the World Health Organisation (who). The latest of these is Omicron, which was given its name in November last year. As Omicron becomes dominant around the world, working out how to protect people from it is becoming more pressing. To do this, scientists must study how different this strain is from those that came before and what that means for immunity, from both previous infection and vaccination.

One question occupying scientists and politicians is whether vaccines would work even better if they were updated to deal with new strains. Up to and including the Delta variant, which was first identified in India and was designated a variant of concern in May 2021, the answer has been “no”. But new research, which has mapped differences between all major versions of SARS-CoV-2, suggests that, although administering existing vaccines is still useful, Omicron is so different from other strains that the answer might now be “yes”.

Source: The Economist  Jan 7 2022.