It’s been almost two months since I first told you about the latest Covid variant, called Omicron BA.2 (Omicron Variant 2.0). What more do we know now than we knew then?
The Omicron BA.2 variant now represents more than half (55%) of new Covid-19 cases in the U.S., according to the CDC. Most of these cases are found in the Northeast. The region has the highest BA.2 concentration, including more than 70% in an area including New York and New Jersey.
U.S. data remains a mix of positive signs, including counts of hospitalized patients near record lows, and some evidence of new pressure as BA.2 spreads. As BA.1 cases decline, the percentage of BA.2 cases is rising. Some epidemiologists are hopefull that built-up immunity in the U.S. population from the winter surge can help mute the BA.2 variant’s impact.
What do we know now about the BA.2 variant?
The BA.2 variant of Covid-19 is a relation of the original Omicron variant, known as BA.1, according to Theodora Hatziioannou, an associate professor of virology at Rockefeller University. The two variants arose around the same time and come from the same ancestor strain. Viruses mutate all the time and diversification within a variant is normal. The earlier Delta variant comprised more than 200 sublineages before it was replaced by Omicron, according to Francois Balloux, director of the University College London Genetics Institute.
Renee Onque and Denise Roland, reporting for The Wall Street Journal, say it still isn’t known whether the BA.2 variant behaves in materially different ways than the original BA.1 variant. Some research suggests it may be more infectious, but like the original, it is less likely to lead to severe disease. Studies in Denmark showed no differences in hospitalization rates when comparing the two. A South African analysis also concluded that the odds of hospitalization and developing severe disease were about the same.
How is the BA.2 variant responding to treatment and vaccinations?
The BA.2 variant may be better at evading monoclonal antibody drugs developed to fight Covid-19, according to New York University virologist Nathaniel Landau. The antibody treatment sotrovimab, which was effective against BA.1, may be less effective against BA.2. The FDA is no longer recommending its use for this newer variant. However, other monoclonal antibody drugs such as remdesivir and molnupiravir, along with the oral treatment pill Paxlovid, have all shown effectiveness against the BA.2 variant.
Vaccines remain effective against both variants. An analysis by the U.K. Health Security Agency found similar vaccine effectiveness against symptomatic disease from both BA.1 and BA.2. Further studies are currently under way.
Where else in the world has the BA.2 variant been detected?
At least 40 countries have detected the BA.2 variant, including the U.K., Denmark, India, Sweden, Singapore, and the Philippines. It appears the BA.2 variant is displacing the BA.1 variant as the original Omicron wave abates and this new wave gathers steam. However, the large number of BA.1 variant cases has left the world with many people who have developed natural immunity, so the BA.2 variant is less likely to be as wide spread. The BA.2 variant has notbeen designated a “variant of concern” by the World Health Organization.