CHARLOTTESVILLE, Va. (WDBJ / UVA release) – UVA researchers have concluded that herd immunity in Virginia “is currently not a plausible means to end the COVID-19 pandemic.” But they believe their finding underscores the importance of vaccines, saying that without them, the herd’s immunity is much further away.
The finding is based on a study in which state-wide COVID-19 blood tests found that only 2% of Virginians had antibodies to the virus in mid-August 2020, a few months after starting the pandemic and before vaccines became available.
Read the full study here.
According to UVA researchers, approximately 2.8 times more Virginians had antibodies than had been identified by state PCR tests. This ratio is lower than many estimates that predict what part of the country’s population may have COVID-19 antibodies.
Participants in the Hispanic study had the highest exposure rate, according to UVA, with more than 10% with antibodies. Other groups with “remarkably higher” rates included residents of northern Virginia (4.4%), those aged 40 to 49 (4.4%), and the uninsured (5.9%). The prevalence by postal code ranged from 0% to 20%. Neighboring zip codes often produce dramatically different results, according to researchers.
“We closely follow the case count, but we must recognize the case count is an underestimation of the actual number of COVID infections,” said Eric Houpt, MD, head of UVA Health’s International Division of Infectious Diseases and Health. “If we use this data to project ourselves today, we would project that as of February 2021, even less than 20% of Virginians could have been exposed to the virus.”
COVID-19 antibody tests
To better understand the spread of COVID-19 in Virginia, UVA Health and the Virginia Department of Health partnered with large hospitals across the state. The researchers tested the blood of 4,675 outpatients from five health systems: UVA Health in the northwest, Inova Health System in the north, Sentara Healthcare in the east, Carilion Clinic in the southwest, and Virginia Commonwealth University in the center. Each site enrolled up to 1,000 residents, over the age of 18, who were not being evaluated for possible COVID-19 infections. According to UVA, participants matched the age, race, and ethnicity of each region
Among the 101 participants who were found with COVID-19 antibodies, 42 were Hispanic. The researchers reported that people with antibodies were more likely to live in multifamily units and that they had contact with a patient who had COVID-19.
The researchers estimated that approximately 66% of the infections detected were asymptomatic.
Previous studies of COVID-19 have suggested that confirmed cases may account for only a small percentage of infected people. Estimates of the total number of unrecognized infections have ranged from six times the confirmed cases to 53 times, so Virginia results were lower compared, according to UVA.
“Virginians are still quite susceptible to this virus,” Houpt said. “We must continue to wear masks in public and practice social distancing and hand washing. I encourage everyone who meets the requirements to receive a vaccine against COVID when they can. “
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