COVID-19 virus BA.2; what is it and why the claim it is more infectious than omicron?

Yesterday the media was flooded with reports about a new variant of omicron designated BA.2. While this virus is almost identical to omicron it is differentiated genetically based on a few mutations in its spike protein. 

Ominously, this virus was reported to be present around the world including throughout the US. This was confirmed by the CDC.

Most experts dismissed this virus as unlikely to cause any worse illness or more hospitalizations and deaths than omicron. In addition, given the structural similarities it is unlikely to be less responsive to antiviral drugs or vaccines.

The biggest news trumpeted about BA.2 was that it was “more contagious” than omicron. This statement was repeated in almost every major news article and mentioned several times by Scott Gottlieb in his media interviews. This increase was even assigned a value; 1.5 times more infectious than omicron.

Trying to find the basis for this “increased infectivity” was very difficult. Most of the news articles did not give a source for this claim but cross referenced each other. Finally, an article in U.S. News clarified that this concern was based on a statement from Statens Serum Institute (SSI), an infectious disease center in Denmark.

Tyra Grove Krause

It turns out that it the increase infectivity concept and number were communicated by SSI’s technical director Tyra Grove Krause in a press briefing. The specific quote given was “we believe there is some indication that it is more contagious, especially for the unvaccinated, but that it can also infect people who have been vaccinated to a greater extent”.

SSI alluded to a study supporting the hypothesis of increased infectivity but no data was provided. It appears the concept emerged because the percentage of COVID-19 infections with BA.2 had increased in Denmark, presumably due to increased transmissibility. Reports are suggesting that BA.2 now accounts for approximately 44% of the COVID infections in that country with standard omicron at 56%.

How this rise occurred in Denmark really is not clear, especially since BA.2 causes a vast minority of COVID-19 infections vs. standard omicron in the rest of the world.

Of interest, Denmark seems to show less concerned than the media about BA.2. On Wednesday the country announced plans to scrap the last of its COVID-19 restrictions by Feb 1, the latest of several countries in Europe to do so. 

This action was taken by the Danes because there are few deaths and “controllable” numbers of hospitalizations from COVID-19 in Denmark despite record high daily infection numbers. This good outcome is thought to be due to the nature of omicron and to the country’s high rate of COVID-19 vaccination and boosters.

So be like Denmark; don’t get scared by the variant announcements. Get COVID-19 vaccinated/boosted and move on with your life.

Published by jbakerjrblog

Immunologist, former Army MD, former head of allergy and clinical immunology at University of Michigan, vaccine developer and opinionated guy.

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