With the world already grappling with the highly infectious Omicron variant of Covid, the discovery of a new sub-lineage at the end of last year gripped the attention of scientists and health officials.
Identified as BA.2, this sub-lineage of Omicron has so far been found in at least 40 countries, including scores of cases in the US. In the UK it now accounts for more new cases than Delta — around 300 in the last week.
