1 in 3 Test Positive for Covid-19 Antibodies in Pilot Massachusetts Street Study

All of the participants “generally appeared healthy,” but around half of them admitted that they had suffered at least one coronavirus symptom in the past month, according to the Massachusetts General Hospital researchers. Those who had previously tested positive for Covid-19 in the regular nasal swab were deliberately excluded from the study.

A total of 64 out of 200 blood samples tested positive for antibodies “linked to COVID-19.” However, Dr. Vivek Naranbhai who conducted the testing, warned that the staggering result does not necessarily mean that up to a third of the Chelsea population had already contracted the virus ― and recovered without even knowing ― and that many of those tested might still be contagious.

Just because you have the antibodies doesn’t mean you’ve cleared the virus.

The researchers used BioMedomics rapid diagnostic device, which has not yet been approved by the CDC and can false-positively react to other types of coronaviruses, but with an estimated accuracy of 90 percent was still deemed reliable enough.

The street study was also very limited in its scale and not representative of the entire population as those staying at home in self-isolation are less-likely to get infected. But the team believes their data could serve as a good indication of the true state of the epidemic and the level of so-called “herd immunity” in Massachusetts’ second most densely populated city.

 “I think it’s both good news and bad news,” the study’s principal investigator, Dr. John Iafrate, told the Boston Globe. “The bad news is that there’s a raging epidemic in Chelsea, and many people walking on the street don’t know that they’re carrying the virus… On the good-news side, it suggests that Chelsea has made its way through a good part of the epidemic.”

The Massachusetts study comes on the heels of a larger antibody research by a Stanford University team, which conducted blood tests on 3,300 residents of Santa Clara County, California and also found that the coronavirus could have infected far more people than has been reported. A Danish study published last week using similar methods arrived at the same conclusion.

Massachusetts is currently the 3rd hardest-hit US state, with over 36,372 officially confirmed Covid-19 cases and 1,560 fatalities, and is under a stay-at-home order until May 4. The researchers plan to conduct more tests in Chelsea and expand the study to other Massachusetts towns, in order to gather more representative data for authorities to make a better-informed decision on lifting the restrictions.