Emerging subvariants are driving Virginia’s rise in COVID-19 cases

For the first time since February, Virginia’s percent positivity — the percentage of lab-tested COVID-19 samples that come back positive — has risen above 10 percent as new infections continue to increase across the state.

Experts say the uptick in cases, which mirrors nationwide trends, is driven by more infectious subvariants of the already highly transmissible omicron strain. Data from the U.S. Centers for Disease Control and Prevention show that nearly 99 percent of new infections in a six-state region that includes Virginia are caused by BA.2 or BA.2.12.1, recently detected variations of the virus.

BA.2 is estimated to be between 30 to 60 percent more transmissible than the original omicron variant, and BA.2.12.1, in turn, is around 25 percent more transmissible than BA.2, according to the CDC.

The continued emergence of new variants is a concern for infectious disease experts after a months-long — and much-needed — lull in cases. COVID-19 infections in Virginia peaked at an all-time high in mid-January but began dropping precipitously soon afterwards, according to data from the state’s Department of Health. March and April marked some of the lowest case rates since the start of the pandemic.

But epidemiologists still aren’t sure whether the state has seen its last major surge. While there’s no evidence that new subvariants cause more severe disease, their enhanced transmissibility is partially due to an uncanny ability to evade protection conveyed through vaccines and previous infections. So while the majority of the country has some degree of immunity through immunization or an earlier case of omicron — or a combination of both — it’s likely not enough to prevent new cases from spreading.

“We know from the fact that cases have doubled that our vaccines and immunity from prior infection are not working that well,” said Dr. Bill Petri, an infectious disease specialist at the University of Virginia. “That’s rubber meets the road — that’s real-world evidence that the vaccines are not optimally protective. There’s an immunity gap today that wasn’t there a month ago.”