Antibodies study: 2.2% of Rhode Islanders were exposed to COVID-19; rates higher in Hispanic, black populations

RHODE ISLAND has announced the results of an antibodies study to determine how much of the population has been exposed to the virus that causes COVID-19. / COURTESY CENTERS FOR DISEASE CONTROL AND PREVENTION VIA THE ASSOCIATED PRESS

PROVIDENCE – A small percentage of Rhode Islanders have been exposed to the virus that causes COVID-19, according to the results of an initial serology, or antibody, study conducted over two weeks in May.

The results, released Friday, indicate just 2.2% of Rhode Islanders have the antibodies that indicate a COVID-19 exposure. The results are much higher for Hispanic residents and black residents.

The study found 8.2% of Hispanic residents tested positive for antibodies, while 5.2% of black residents did so.

The results were determined by a randomized survey, which asked 5,000 households to undergo testing for the antibodies at their choice of several Stop & Shop locations. About 10% to 15% of the people participated, which was a number the state said was satisfactory.

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The R.I. Department of Health conducted the testing, with analysis by Brown University. The test was considered accurate, to a 99% confidence interval, and was not thought to react to more common coronaviruses, which could cause a false positive on the test.

The prevalence overall was lower than the testing team anticipated, according to Dr. Philip Chan, consultant medical director for the division of preparedness, response, infectious disease and emergency medical services at the R.I. Department of Health.

“A lot of people thought it would be higher, but it’s not,” he said. “It means a lot of Rhode Islanders are still potentially susceptible to COVID-19.”

The results underscore that Rhode Island is nowhere near achieving herd immunity. 

That’s the point at which a virus starts to disappear because enough people have either contracted it, and are immune, or had a vaccine. In the case of COVID-19, although numerous companies are working on vaccines, none of that work is complete.

An important point, Chan said, is that the extent of ‘immunity’ for people with antibodies to the virus is an area of research. No one is really sure at this point whether people who have antibodies to the virus are protected from reinfection.

“We don’t know if having antibodies” confers protection from COVID-19, he said.

The antibody, or serology, test is a blood test. All of the people who were tested for antibodies had no symptoms of the COVID-19 infection, but were asked about their health history and any previous symptoms in past months. The state will keep in touch with the people who tested positive for the antibodies, to determine if they in the future contract the virus, Chan said.

“What do these numbers mean? 2.2% means the numbers are still relatively low in Rhode Island,” Chan said. “… People need to keep protecting themselves, adhering to social distancing and mask requirements.”

Mary MacDonald is a staff writer for the PBN. Contact her at

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