Virginia National Guard soldiers and airmen support a community vaccination clinic opened April 19, 2021, by the Virginia Department of Health and the Virginia Department of Emergency Management. (U.S. National Guard photo by Cotton Puryear)
Nearly 18 months after Virginia’s first recorded case of COVID-19 — a period that’s seen the virus surge and retreat four different times — new infections are once again on the decline. Once again, many researchers are cautiously optimistic that we’re leaving behind the latest wave, driven by the highly infectious delta variant, which raised hospitalizations in some areas of the state higher than they were last winter.
That doesn’t mean we’ve beaten the virus.
“We still have a very high case rate, like most of the states in the country,” said Bryan Lewis, a computational epidemiologist with the University of Virginia’s Biocomplexity Institute. “We’ve been down for a few weeks, so everybody feels good, but there are still a lot of people going into the hospital.”
As of Friday, Virginia was still recording an average of more than 2,000 new infections a day. More than 1,500 patients are hospitalized with coronavirus in the average week, according to data from the Virginia Hospital and Healthcare Association. Those figures seem particularly stark compared to this summer, when daily new cases dropped below 150 and COVID hospitalizations reached an all-time low.
Delta’s continued circulation means it’s no time to fully relax precautions, according to scientists. But there’s also reason to think the future may be brighter than it was at the beginning of last holiday season, which started the state’s worst surge several weeks earlier than many experts first anticipated.
For much of the pandemic, the Biocomplexity Institute has been modeling the likely trajectory of COVID-19 in Virginia using mobility data, case rates, vaccination numbers and a slew of other statistics that can predict how, where and how fast the virus will continue to spread.
With many Virginians — and public health officials — already preparing for holiday gatherings, understanding potential risks could be crucial for decision-making.
“We’re at the point where community immunity can start to help,” Lewis said. “It’s like little firebreaks. And the tricky part is, it’s hard to really map out where those firebreaks are.”
A slow holiday decline
The fact that those firebreaks exist, though, make the current outlook much brighter than it was at the same time last year. While many public health experts were hoping vaccine acceptance would be more widespread — and happen faster — than it did in Virginia, the fact remains that just over 73 percent of the state’s total adult population is now fully vaccinated, according to the Virginia Department of Health.
While rates are significantly lower in some parts of the state, there are still thousands of vaccines being administered every day. And the nearing prospect of vaccinations for children under 12 could boost immunity across the entire population.
“One should not expect huge jumps,” said Madhav Marathe, the director of the Biocomplexity Institute’s Network Systems Science and Advanced Computing Division. “But the federal mandates might give us a bump, children are a bump and all of these things are important.”
The slow-and-steady campaign has already resulted in more than 5 million fully vaccinated Virginians. On top of that, there are also thousands of people with natural immunity from previous COVID-19 infections. While it’s not totally clear how long that natural immunity provides protection, we’re beginning this fall with much higher protection than we did last year, before vaccines were available. That makes it unlikely we’ll see the same drastic spike that the state experienced last winter, when VDH recorded dozens — and sometimes hundreds — of new coronavirus deaths every day.
Still, Lewis estimated there’s at least a million Virginians who haven’t been vaccinated but also haven’t been infected yet (or were infected so mildly, or so long ago, that natural immunity likely won’t protect them from the disease). Those are the people who are most vulnerable to contracting the virus and causing new outbreaks over the next few months, especially if they’re not taking precautions such as masking or avoiding indoor gatherings.
“It’s enough people that this thing could kind of simmer along,” Lewis said. “And I think that’s the phase we’re entering into.” Models predict the state could continue to see small spikes through the winter, even as overall case rates trend down. But it’s still not totally clear where the most vulnerable populations are living or how they’ll interact with other people, making it difficult to predict where exactly those waves might occur.
“To the extent it happens, it’s likely to happen in pockets,” Marathe said. “I don’t think we’ll get a statewide, large-scale thing, at least for the time being.”
Looking past this winter
As for what could happen after this winter, experts say that’s much harder to predict. As The New York Times reported, both Britain and Israel are continuing to struggle with outbreaks even with higher vaccination rates than the United States — what one expert described as a “wake-up call.” And while evidence indicates that available vaccines are highly protective against severe illness and death, it’s becoming more clear that they’re not as effective at preventing infections from the delta variant.
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Vaccine-conferred immunity against infections also appears to wane over time — evidence that prompted the recent approval of Pfizer booster shots and recommendations for boosters of both the Moderna and Johnson & Johnson vaccine. But there’s still debate over how long it takes for immunity to wane and the best spacing for the shots.
Lewis said the Biocomplexity Institute is in the process of tweaking its models to account for waning immunity, both from vaccines and previous infections. But with so much unknown, it’s difficult to anticipate how the virus might continue to spread.
“It’s really difficult to measure and we’ve been having a lot of conversations about that,” he said. The prospect of a new variant is also a “looming spectre” for scientists, according to Marathe. Even with vaccination rates that are higher than the national average, nearly one out of every five adults in Virginia still isn’t immunized against the virus. Vaccination rates are substantially and worryingly lower in many countries, which can affect the world as a whole. As long as the virus continues to circulate among hosts, there’s a chance it could evolve into a strain even better at evading immune responses.
“This can come back in a form that is even more deadly, for all we know, and we could again get a certain surge,” Marathe said. “And my hope is that it wouldn’t be so different, so our immunity, even if it’s weaker, would help us.”
It’s why there’s still such urgency in the push for vaccines. No immunization is completely effective against so-called “breakthroughs” — cases of the disease among the fully vaccinated. But there’s ample evidence, including the state’s own data, that the risk of hospitalization and death is far, far lower for those protected by the vaccine.
Vaccinations can also slow the spread of the virus far faster than waiting for people to get infected and develop natural immunity. Scientific advances, including monoclonal antibodies and a new antiviral therapy developed by Merck, are already reducing the deadliness of the virus for people who have contracted the disease. But boosting immunity through vaccinations can also slow COVID-19’s ability to develop into new strains — effectively removing new hosts for the virus to infect.
Both Marathe and Lewis said it’s possible the disease could eventually become endemic in the same way as the seasonal flu. While new variants would continue to develop, human immunity would largely keep pace, in large part because of previous vaccinations or exposures. The same thing happened with the 1918 flu, which eventually evolved into descendants that we still experience today.
“If you want to anthropomorphize it a bit, COVID right now is like a clumsy, awkward teenager,” Lewis said. “Lots of energy, very reckless. But as it gets older, it gets worn down by the collective immune system of the human population.
“It sort of learns, ‘As long as I transmit but I don’t kill people, then I can have more babies,’” he added. “And those strains will thrive more than the ones that put you in the hospital and kill you off.”
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