New omicron BA.2 variant more transmissible but vaccines are more effective against it
The omicron BA.2 variant is slightly more transmissible but vaccines are more effective against it, the first official data from the UK Health Security Agency (UKHSA) has found.
Genetic screening has found 1,072 cases of the variant as of January 24 and say case numbers are still low compared to the main omicron strain.
The UKHSA said BA.2 appeared to have an increased growth rate, and infected people had a slightly higher risk of passing it on to household contacts.
Between December 27 and January 11, household contacts became infected in 13.4 per cent of BA.2 cases compared to 10.3 per cent with the original strain.
However, experts have warned that transmission rates are often higher when a variant is first identified and may come down.
Vaccine effectiveness after two doses was nine per cent for the omicron variant and 13 per cent respectively for BA.2 after 25 weeks, but two weeks after the third vaccine, it rose to 63 per cent for the original and 70 per cent for BA.2.
There is still no data on the severity of BA.2 but experts said there was nothing yet to worry about.
‘So far, it’s nothing to worry us unduly’
Jonathan Ball, Professor of Molecular Virology at the University of Nottingham, said: “The key issues are whether this variant is associated with more severe disease and if it can escape immunity delivered by vaccines.
“Early indicators suggest that the vaccines will provide similar levels of protection as we have seen for omicron, so this is good news. Whether or not it causes more severe disease will become apparent as more data is collected.
“Of course, it is important to keep monitoring the situation and try to gain a better understanding of how this variant behaves, but so far there is nothing in these early analyses to worry us unduly.”
The new UKHSA report also confirmed that the recent rise in coronavirus infections in care homes has not led to an increase in hospital admissions.
Health officials said the 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 or natural immunity.
Professor John Edmunds, an epidemiologist at London School of Hygiene & Tropical Medicine, said it was possible that BA.2 could take over from the original omicron strain in the next few weeks, as it has done in Denmark.
He added: “The good news is that, at present, there is no evidence to suggest that it is more severe than omicron and as the UKHSA analysis shows, the vaccines appear to be as effective against it as they are against BA.1.”
