A Harvard epidemiologist is warning more research is needed to determine when people infected with the coronavirus produce antibodies that might protect them from reinfection.
“We don’t know yet at an individual level just what the risk of reinfection is and how protected or not somebody might be,” Dr. Michael Mina, assistant professor of epidemiology at the Harvard T.H. Chan School of Public Health, said during a live Facebook Q&A. “We have to do the studies to really understand what level of partial immunity people might have after being infected.”
Boston officials said that a study to evaluate community exposure to COVID-19 through a representative sampling of asymptomatic residents found that about 1 in 40 tested positive for the disease and 1 in 10 had developed antibodies.
It is hoped that one way to determine the extent to which the pandemic has spread is the use of antibody tests, which can help detect if someone already has been exposed to the coronavirus. Tests now available on the market may help health-care professionals, researchers, government officials and the public at large as society begins to reopen.
However, questions have emerged about the accuracy of the tests, as well as their role in ascertaining important factors, such as future immunity.
“One of my big concerns is that people might get an antibody result back that’s positive. They might throw away the mask and go see grandma and grandpa in the nursing home, not recognizing that just having an antibody-positive test does not necessarily mean that you can’t still acquire the virus again and transmit it onto grandma and grandpa in the nursing home or elsewhere,” Mina said.
Other tests available now are “really quite powerful,” he said.
“Instead of just giving us a yes or no answer — does this person have antibodies or not — we actually have tests that … can give you a quantitative value,” Mina said. “They can tell you how much antibody is measured in your blood.
“(But) at this moment in time, I won’t know how to interpret the level of protection,” he said. “That means we have to do the studies where we follow people over time who have antibodies, and we stratify them. … Do one of those groups get infected and sick again and another one not. And that will help us start to differentiate and figure out, are there levels of antibodies above what you’re protected and below what you might not be?”
Test results also can help officials determine how to best allocate resources to public health needs and know where they need to do the most enhanced surveillance, such as places where there’s a large immunity gap, Mina said.
“And you might really want to worry about those,” he said, “as being the next places where you might see a big outbreak.”
