Omicron has been responsible for nearly all new infections in the U.S. since January. While both BA.2 and BA.1 can be traced back at some of the earliest Omicron samples, BA.2 is only now starting to rise in prevalence.
According to the CDC's "Nowcast", published Tuesday, BA.2's prevalence in the Northeast is highest. The agency estimates that 39.0% of the circulating viruses in the New York-New Jersey region are BA.2. BA.2 prevalence in New England is 38.6%
These new estimates are coming as concerns have been raised about the sub-lineage abroad. It has now dominated cases reported worldwide, including in countries that are now experiencing a renewed surge in infections. This is just as many countries had lifted their pandemic restrictions.
China's authorities are reimposing strict lockdowns in an effort to stop the spread of BA.2 infections in many cities.
The increase in BA.2's in the U.S. coincides with the CDC continuing to track a slowdown in new COVID-19 hospitalizations as well as cases.
These trends seem to be true even in regions with the highest proportion of BA.2 cases. However, early-warning data collected by the agency using wastewater samples suggests that some communities may soon experience an uptick.
"Although there is an increase in infections with BA.2 in the U.S. COVID-19 cases are declining so it is possible that the absolute number of BA.2 infection is not increasing as fast as you might think based on just the percentage that are BA.2," Dr. Deborah Dowell (CDC's chief medical office for COVID-19 response) stated over the weekend.
Dowell spoke at an webinar that was hosted by the Infectious diseases Society of America. Dowell said that a key difference in BA.1 and BA.2 allowed some researchers to "quickly distinguish these sub-lineages."
As with the Alpha variant which was discovered in 2020, BA.1's mutations were and caused an error during some COVID-19 testing. Authorities were able to quickly identify Omicron cases, and estimate Omicron's rise in the future by using this "S-gene Target Failure" which was not caused by most Delta variant cases.
BA.2 doesn't cause the same failure. Some misleadingly call it a "stealth variation". Researchers are now able to quickly analyze BA.2's growth, even though BA.1 was exhibiting nearly 100% new infections in the first quarter of this year.
"While BA.2 seems to be growing in terms of sub-lineages in America, it's not as fast as in other countries. Dowell stated that the doubling of time in the United States seems to be slowing.
Health authorities in the United Kingdom recently determined that BA.2 is now responsible for most new infections in the majority of areas of the country.
Dowell later added that while there is speculation that Omicron may see a steepening of the curve, it is unlikely that Omicron will experience another surge like we did initially with Omicron.
Federal health officials state that BA.2 is "highly on our radar"
Research done so far from Qatar as well as Denmark suggests that BA.2 will not cause a lot of reinfections in people who have survived the Omicron wave. The South Africa as well as the United Kingdom have shown that the BA.2 variant is about the same risk for severe disease and evading vaccine protections than BA.1.
These similarities were cited by the World Health Organization late last year, which stated that it would continue to consider both BA.1 & BA.2 as one variant of concern.
It is vital to track the spread of BA.2 in order to change the treatment options available for COVID-19 patients who are most at risk.
A rise in BA.2 could prove to be a boon to those looking for Evusheld, an AstraZeneca antibody drug that is used to treat immunocompromised Americans. BA.2 seems to have "nearful susceptibility" to Evusheld. However, the Food and Drug Administration warned recently that doses would need be doubled in order to protect against BA.
A rise in BA.2 cases could lead to the discontinuation of sotrovimab (a monoclonal anti-body drug manufactured by GlaxoSmithKline, Vir Biotechnology). The effectiveness of treatment could be reduced by BA.2 according to early laboratory research.
"BA.2" is on our radar," Dr. Derek Eisnor (federal official responsible for leading distribution of COVID-19 drugs at Department of Health and Human Services) said in a webinar last.
Eisnor acknowledged that new monoclonal antibodies variants present an "Achilles heel", but pointed out other options, like the COVID-19 Antivirals Pills from Merck and Pfizer. These antivirals are still effective in treating BA.2 infections.
Eisnor stated, "I believe in the future, we may be handicapped by some of our monoclonal antibodies becoming inefficacious, again being on pause or having to limit their use, this will be where our oral antivirals really shine and hopefully that helps a bit."
