Stealth Omicron BA.2 spread faster than BA.1 but there’s a catch: UK study

“While growth rates can be overestimated in early analyses of a new variant, the apparent growth advantage is currently substantial,” the UK Health Security Agency (UKHSA) pointed out. As of January 24, 1,072 genomically confirmed cases of BA.2 have been identified in England alone. 

How fast the BA.2 variant of Omicron is spreading? 

As per UKHSA, contact tracing data showed transmission is likely to be higher among contacts of BA.2 cases in households at around 13.4% than those for contacts of other Omicron cases at 10.3%.

“We now know that BA.2 has an increased growth rate which can be seen in all regions in England. We have also learnt that BA.2 has a slightly higher secondary attack rate than BA.1 in households,” said Dr Susan Hopkins, Chief Medical Advisor for UKHSA.

“Although hospitalisations and deaths remain low, cases are still high in some areas and some age groups so it’s important that we continue to act cautiously as restrictions are lifted,” she said.

How effective are the vaccines on BA.2 variant? 

After two doses, vaccine effectiveness was 9% and 13% respectively for BA.1 and BA.2, after 25 weeks. This increased to 63% for BA.1 and 70% for BA.2 at 2 weeks following a third vaccine.

Can Omicron cause severe illness?

The UKHSA said its findings suggest the current wave of Omicron infections is unlikely to lead to a major surge in severe disease in care home populations with high levels of vaccine coverage and/or natural immunity.

Expert around the world suggests that BA.2 strain has been found in more than 50 countries. The mutant appears much more common in Asia and Europe. In Denmark, it has spread quickly and become the dominant variant.

Earlier this week, India government had pointed out, the BA.2 subvariant of the Omicron coronavirus is more prevalent in India now.

(With inputs from agencies)