PORTLAND, Ore. – Oregon Health Authority released a coronavirus study on Friday indicating that a “substantial” portion of Oregonians have had an undiagnosed and unreported case of COVID-19.
The study, authored by OHA epidemiologists, found that 1% of Oregonians that don’t have COVID-19 had evidence of past infection of the virus in their blood.
Officials say this is 10 times higher than the reported rate of infections found through conventional testing.
“We suspected that a much larger segment of Oregon’s population has been exposed to and infected with COVID-19 than traditional diagnostic testing shows,” said Paul Cieslak, M.D., a study co-author and OHA medical director for communicable diseases and immunizations. “But these results also tell us that the great majority of Oregonians remain susceptible to this virus.”
Nine of the 897 blood samples collected form 19 health care facilities across Oregon between May 11 and June 15 contained antibodies against the virus that causes COVID-19.
The rates of infection were shown to increase with age, with no antibodies found in the blood of pediatric patients 17 and younger.
Oregon’s first case of coronavirus was diagnosed Feb. 28. Through May 31, 4,243 people had tested positive, but this data doesn’t account for people who did not seek testing.
“Because most of us are still susceptible,” said Cieslak, “we need to keep practicing physical distancing and masking until we have effective vaccines, treatments or other means of mitigating illness.”
Antibodies don’t appear in your blood until two to three weeks after exposure to the virus, Cieslak said. He added at this time experts are not sure if having antibodies ensures protection against COVID-19.
For more information on antibody testing, visit the CDC website.