PORTLAND, Ore. – The Oregon Health Authority released a coronavirus study on Friday that found a “significant” portion of Oregonians had an undiagnosed and unreported case of COVID-19.
The study, authored by OHA epidemiologists, found that 1% of Oregonians who did not have COVID-19 had evidence of previous infection of the virus in their blood.
Officials say this is ten times higher than the reported infection rate found through traditional testing.
“We hypothesized that a much larger proportion of Oregon’s population was exposed and infected with COVID-19 than conventional diagnostic tests show,” said Dr. Paul Cieslak, study co-author and OHA medical director for communicable diseases and vaccinations. “However, these results also show that the vast majority of Oregonians are still susceptible to this virus.”
Nine of the 897 blood samples taken at 19 health facilities in Oregon between May 11 and June 15 contained antibodies to the virus that causes COVID-19.
Infection rates have been 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 on February 28. By May 31, 4,243 people had tested positive, but this data does not include people who did not seek tests.
“Because most of us are still vulnerable,” said Cieslak, “we must continue to practice physical distancing and masking until we have effective vaccines, treatments, or other means of disease relief.”
Antibodies don’t appear in your blood until two to three weeks after exposure to the virus, Cieslak said. At this point, experts are not sure whether antibodies guarantee protection against COVID-19.
For more information on antibody testing, see the CDC website.