Omicron: what do we know about ‘stealth’ subvariant BA.2?

A health worker with a Covid vaccine syringe in Brazil. Some early reports suggest the Omicron variant BA.2 may be more infectious than the extremely contagious BA.1, but there is no evidence so far that it is more likely to evade vaccine protection. Photograph: Carl de Souza/AFP/Getty Images

The highly transmissible Omicron variant of the Sars-CoV-2 virus – the most common form of which is known as BA.1 – now accounts for nearly all of the coronavirus infections globally.

Though Covid cases have already peaked in some countries, scientists are now tracking a rise in cases caused by a close cousin of Omicron known as BA.2, which is starting to outcompete BA.1 in parts of Europe and Asia. The following is what we know so far about the new subvariant.