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UVa research: Two out of three people in the summer were asymptomatic

Researchers who tested nearly 4,700 Virginians from June to mid-August for traces of a prior coronavirus infection found that only about 2.4% had previously been sick.

But two out of three of those who had contracted the virus didn’t have any symptoms. And when adjusted for population, the numbers were nearly three times higher than summer reports of positive tests on the Virginia Department of Health website.

This indicates that the number of COVID cases, as expected, is likely much higher said Dr. Eric Houpt, infectious disease expert at University of Virginia Health who co-authored the report.

When someone is completely asymptomatic, he said, “you’re very unlikely to test them and to detect them, because why would they get tested in the first place, unless they were being tested through some screening mechanism?”

Findings showed that less than 20% had taken a COVID-19 test and only 1% of total adults in the study ever received a previous positive test result. The Centers of Disease Control and Prevention released a study the first week of January with similar results. It found 60% of transmission may be coming from asymptomatic individuals.

“We’ve always known that we’re missing a lot of infections because we don’t have daily testing on every single person in the state or in the community or anywhere,” Houpt said. “That three-fold number is not surprising. Some studies have found that it’s up to 10 [times] more.”

Virginia’s total caseload of positive test reports is at 553,308 as of Tuesday. If multiplied by 2.8, which researchers found was the difference when adjusted for population, the state would have more than 1.5 million cases.

With highly transmissible variants likely to become the dominant virus strain in March, months after the state’s deadliest month in January, Houpt urged residents to be careful and continue wearing masks and social distancing.

A Friday report from scientists in the United Kingdom, where one variant first originated, found an increased risk of hospitalization and death. Research is ongoing.

“The virus is still here,” Houpt said. “It’s foolish to predict too far ahead with this thing. It’s been unpredictable from the beginning. It’s far too early to conclude that we’re on the tail end of this. We have a long way to go.”

The COVID-19 serology project—conducted in tandem with the VDH and four other major health systems across the state including VCU—released its initial results in September. Participants were patients who sought out medical care for non-virus-related reasons.

Published in the journal JAMA Network Open last Monday, the finalized research expanded upon its earlier estimates.

In September, the study noted that Latinos were four times more likely to have traces of a prior infection than the average Virginian. While that didn’t change, the latest release noted the likelihood that Latinos make up nearly 42% of the state’s cases. At the time of the study, they accounted for less than 34%.

The findings also showed a potential 20% difference between ZIP codes, even ones next to each other.

Houpt said geographically, researchers noted that people in Northern Virginia had higher rates of antibodies—as did residents without health insurance, limited access to care and those living in more crowded housing.

A limitation to the study is that antibody studies are less reliable than diagnostic COVID-19 tests, which measure the active presence of the virus, while antibody tests which point to signs that the body has fought off a past infection.

But the results track from where current cases are. In Richmond, ZIP codes in South Richmond and the city’s East End—which hold the largest non-white populations in lower-income areas—were 60% of COVID cases from Dec. 14 to Feb. 3. They were also the farthest from established vaccination sites.

Less than five miles away, a more affluent ZIP code that is 87% white had the second-lowest number of cases.

Vaccine update

Virginia has administered nearly 1.4 million shots. Almost 95% of vaccines allotted for first doses have been given. For second doses, it’s more than half.

At least 351,441 people have been fully vaccinated and 12.3% of the state’s total population has received at least one dose. The state is averaging almost 35,000 shots given each day over a seven-day period.

The state has consistently surpassed the national average for weeks in a sharp improvement from its first month of the rollout. As of Tuesday, Virginia was 7th in the country for percentage of supply used.


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