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.”

What exactly that means for the future, though, is still largely unclear. Despite the immune-evading capabilities of new viral variants, existing vaccines still appear largely effective against severe outcomes including hospitalization and death. 

Experts still can’t fully explain why, but Petri said the most likely theory is cellular immunity — another type of vaccine-conveyed protection. Omicron and other subvariants have mutations along the spike protein that allow them to largely evade the antibodies triggered by immunization. Those adaptations make it easier for the virus to invade cells, but vaccination also spurs other forms of immunity once it’s there.

“It’s hard for antibodies to be very effective once an infection has started because they’re only binding to the virus outside cells,” Petri said. “Whereas the cellular immune system is able to kill virus within cells.” While the mechanism isn’t fully understood, state data shows that unvaccinated Virginians are still hospitalized at twice the rate as fully vaccinated residents and the death rate for the unvaccinated is roughly 14 times higher.

So far, COVID-19 hospitalizations in Virginia have risen along with cases but still remain at historically low levels. Statewide, deaths are also on the decline despite rising infection numbers. Like other experts, Petri emphasized that the virus has become less deadly over time thanks to vaccines and dramatically improved treatments such as the antiviral Paxlovid, which is now widely available in pharmacies and can dramatically reduce the chance of hospitalization and death.

In some ways, those medical advancements have made the prospects of the pandemic more murky. Just over 73 percent of Virginia’s total population is vaccinated with two doses, and researchers are hopeful that existing protection will lessen the severity of any future surges. In a recent report, researchers from UVA’s Biocomplexity Institute noted that BA.2.12.1 could cause a “significant number” of new COVID-19 cases, but peaks are expected to be lower than they were during January’s omicron surge.

Still, they noted that every new infection carries the risk of hospitalization, especially in light of waning vaccine protection and immune-evading variants. As of Wednesday, less than half of fully vaccinated Virginians had received a third dose, which is widely regarded as vital to boosting immunity and providing more protection against emerging variants. The Washington Post reported last week that waning protection is also contributing to a growing share of COVID-19 deaths among the vaccinated — mostly elderly and immunocompromised patients already at increased risk for severe disease.

The majority of vaccinated deaths were among patients who weren’t boosted, and the unvaccinated are still the most likely to die from the disease. With varying rates of protection across the state, rising transmission raises the possibility of a new surge in hospitalizations and deaths that could disproportionately impact the most vulnerable. 

“These variants do concern me, that we could again have pandemic levels of COVID-19 especially as we get out of the springtime,” Petri said. “Which is when we’ve historically seen low levels of transmission.” 

As of last week, cases were rising in more than half of the state’s 35 health districts even though transmission levels in most are still low to moderate. As pandemic-weary Virginians continue to navigate an uncertain future, Petri said keeping an eye on the metrics is the best way to maintain a sense of normalcy. 

While Virginia no longer has COVID-19 restrictions in place, masking in indoor settings and social distancing are still an easy way to reduce the risk of transmission, he said. Cutting back on social gatherings is another way to respond to rising case rates, as is testing and isolating even in the case of mild symptoms. Still, Petri said continued advancement in vaccines and treatment have put the state in a far better place than it was at the start of the pandemic.

“The horizon is just a little bit cloudier,” he said. “It looks like a storm is brewing once again because of the amazing and terrible ability of this virus to mutate into variants that have a selective advantage.”