What do we know about “invisible omicrons” so far?

It’s a more contagious version of the omicron variant, but it doesn’t seem to cause more severe disease.

BA.2 has been spreading globally since it was first detected in November, driving new surges in parts of Asia and Europe. It is now the main version of the coronavirus in the US and 5+ other countries.

It was given the nickname “stealth” because it looked like an early delta variant in some PCR tests, said Kristin Coleman of the University of Maryland’s School of Public Health. In contrast, the original omicron is easily distinguishable from delta because of a genetic quirk.

In rare cases, early research has shown that BA.2 can infect people, even if they are already infected with omicron. The COVID-19 vaccine appears to be equally effective against both omicrons, offering robust protection against severe disease and death.

Health officials are also tracking other variants, including XE – a combination of BA.2 and BA.1, the original omicron – which was first spotted in the UK in January. The World Health Organization is watching XE closely, but has yet to see it as a variant of concern or interest.