UKHSA says BA.2 subtype has an apparent transmission advantage

 According to the UK Health Security Agency, the BA.2 subtype of the Omicron coronavirus variation looks to have a significant growth advantage over the currently dominating BA.1.

In all locations of England where there were enough cases to compare, BA.2 had a higher growth rate than BA.1, according to UKHSA, and "the apparent growth advantage is presently considerable."

"We now know that BA.2 has an increased growth rate which can be seen in all regions in England," said Dr Susan Hopkins, Chief Medical Advisor for the UKHSA.

According to the FDA, there is no data on the severity of BA.2 compared to BA.1, but a preliminary review found no difference in vaccination efficacy against symptomatic illness between the two Omicron subtypes.

The fast spread of BA.1 fueled an Omicron wave that drove cases to new highs in December in the United Kingdom, replacing the previously dominant Delta strain.

However, due to population protection from vaccination and past illness, as well as Omicron's reduced severity, hospitalizations did not grow to the same amount.

According to the UKHSA, a different study revealed that between November 24 and January 19, the majority of COVID-19 critical care admissions had Delta infections, despite Omicron infections dominating the number of cases.

It was also discovered that an increase in Omicron cases in care homes was not linked to an increase in hospital admissions.

"Our findings suggest that the current wave of Omicron infections is unlikely to result in a major surge in severe disease in care home populations with high levels of vaccine coverage and/or natural immunity," UKHSA said, noting that the study's findings were based on BA.1 cases due to a lack of BA.2 cases. 

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