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Will people who have been exposed to the coronavirus be immune for life, like the measles, or will the disease return again and again like the common cold? NPR science correspondent Richard Harris says that key question is at the heart of rapidly evolving scientific studies.
RICHARD HARRIS, BYLINE: Most people who get sick with the coronavirus develop antibodies as part of the immune response. But are antibodies actually protecting people from further infection? And if so, for how long? Jeffrey Shaman at Columbia University is one of many scientists exploring that.
JEFFREY SHAMAN: This, to me, is one of the big unanswered questions that we have because it really says, what is the full exit strategy to this, and how long are we going to be contending with it?
HARRIS: Best case - people will be exposed or immunized once and then be able to put the coronavirus behind them for the rest of their lives. A simple blood test could herald that good news. But Shaman isn't betting on that. He's been studying four other coronaviruses that cause the common cold. Ninety percent of us have antibodies to those viruses.
SHAMAN: They're very common. And so people seem to get them quite often. And our evidence suggests that those antibodies are not conferring protection.
HARRIS: In some diseases, people with milder infections are less likely to mount a strong immune reaction and less likely to develop immunity. So one scenario is that people with mild cases of COVID-19 won't be immune but people with more severe cases will be. But that's just a hunch.
AKIKO IWASAKI: Unfortunately, we cannot really generalize what kind of immunity is needed to protect a person against a virus unless we really learn more about the virus.
HARRIS: Immunobiologist Akiko Iwasaki at the Yale Medical School is part of a rapidly expanding effort to figure this out. She and her colleagues are already studying the immune response in more than a hundred patients at Yale. She's encouraged to note that most people who recover from COVID-19 develop antibodies that neutralize the coronavirus in a petri dish.
IWASAKI: Whether that is what's happening inside the body, we don't really know.
HARRIS: Studies like hers will answer that question eventually, but not all antibodies are protective. Iwasaki says that some can actually contribute to the disease process and make the illness worse.
IWASAKI: Which types of antibodies protect the host versus those that enhance the disease, we really need to figure that out.
HARRIS: And how long will the protective antibodies last? Will it take a full year of studying people to figure out if they are protected for a year?
IWASAKI: Yeah, I wish there was a shortcut. But you know, we may not need to wait for a year to understand what type of antibodies are protective.
HARRIS: She is one of many scientists looking for patterns in the immune response that would indicate long-term immunity. Dr. Kari Nadeau at Stanford is also examining blood samples from hundreds of people who have recovered from COVID-19. Nadeau says it's important to figure out whether the immune response can completely stop the virus from multiplying.
KARI NADEAU: Because you might be immune - you might have protected yourself against the virus, but it still might be in your body and you're giving it to others.
HARRIS: That would have huge public health implications if it turns out people can still spread the disease long after they've recovered. There's nothing definitive on that as yet. Nadeau is also trying to figure out what could be said about the antibody blood tests that are now starting to flood the market. People would love to know if a true positive test means they have long-lasting immunity that would allow them to return to work safely.
NADEAU: I see a lot of business people wanting to do the best for their employees and for good reason. And we can never say you're fully protected until we get enough numbers. But right now we're working hard to get the numbers we need to be able to see what constitutes protection and what does not.
HARRIS: It could be a matter of life or death to get this right. Fortunately, many labs are now working simultaneously to figure that out.
Richard Harris, NPR News. Transcript provided by NPR, Copyright NPR.
