Omicron BA.2 subvariant is growing but may not pose a serious threat

PITTSBURGH — A subvariant of omicron is now driving a surge in COVID19 cases in the United Kingdom, Europe and parts of Asia, but in Western Pennsylvania, health experts don’t foresee another dramatic wave of infections.

The subvariant, known as BA.2, isn’t new; it first emerged in November and has been circulating in Pennsylvania and the rest of the United States for more than two months. At a time when overall coronavirus cases are declining across the country, the prevalence of BA.2 has doubled over the past two weeks. The subvariant now makes up about 35% of cases nationwide, according to the Centers for Disease Control and Prevention.

Scientists have been keeping an eye on BA.2 because it’s even more contagious than the original omicron strain, known as BA.1, which was responsible for record-high case counts, hospitalizations and deaths in early January. The BA.2 subvariant does not seem to cause more severe disease than its parent strain.

“The bottom line is, we’ll likely see an uptick in cases, as we’ve seen in the European countries, particularly the U.K.,” White House chief medical adviser Dr. Anthony Fauci told ABC’s “This Week” earlier this month. “Hopefully we won’t see a surge — I don’t think we will.”

State health authorities in Pennsylvania are also hopeful that cases will remain low for a while, and they are not anticipating more hospitalizations or deaths due to BA.2.

“While the department cannot rule out the possibility of a surge in cases due to BA.2, we are not anticipating a surge in cases comparable to the omicron surge in late 2021 and early 2022, and there is no evidence to suggest that hospitalizations or deaths would dramatically increase,” said Mark O’Neill, spokesman for the Pennsylvania Department of Health.

In Allegheny County, the health department reported that about 10% of COVID19 cases during the week of March 13-19 were due to the BA.2 variant. The week before, BA.2 made up about 6% of cases. The county began testing a portion of positive cases for variants in January.

“The rate of increase of BA.2 seems to be slower here than it is elsewhere,” said Vaughn Cooper, a microbiologist at the University of Pittsburgh. “I’m cautiously optimistic that we’re not going to see a true surge, largely because its timing is coinciding with better weather and more outside time.”