Though COVID-19 has been circulating for nearly a full year, there's still so much we don't know about the virus. We don't know why some people develop severe symptoms while others remain asymptomatic, for instance. We also don't know what the long-term effects of COVID-19 are. One area of special interest, though, is around immunity: Are people who've recovered from the virus immune to it going forward?
While it seems likely, for now, experts are super-clear about the fact that we (wait for it) don't know much about immunity — including how long it might lasts after recovering from the virus. "Nobody can claim long-term immunity to COVID-19 because we haven't known about COVID-19 long enough to make these types of claims," says Jessica Malaty Rivera, MS, infectious disease epidemiologist and science communication lead at The COVID Tracking Project.
The Centers for Disease Control and Prevention says that the antibodies produced in response to the virus might protect you for around 90 days after the onset of infection. But they also state, "Whether you test positive or negative for COVID-19 on a viral or an antibody test, you still should take steps to protect yourself and others. We do not know how much protection (immunity) antibodies to the virus might provide against getting infected again."
Dr. Rivera compares antibody tests to looking in the rearview mirror of your car. "It's something that happened in the past, it doesn't change anything about the present or the future. And, a lot of times, they're not very accurate," she says. "You should not look at your antibody status as an immunity passport because that's not what it is." She, like the CDC, emphasizes the importance of following basic prevention guidelines regardless of antibody status: "It should never change anybody's public health mitigation behaviour. You shouldn't stop wearing masks or physical distancing and start doing high-risk activities."
That said, some recent research indicates that you may continue being immune even after antibody levels drop off. "Cellular immunity" may be still present six months after having mild or asymptomatic COVID-19, a small study out of the U.K. indicates. It found that T-cells (a key player in the immune system) continued to have a strong response to the presence of the virus, even after antibody levels started dropping. This study hasn't yet been peer-reviewed, and it looked at just 100 people, so the results must be taken with a grain of salt. But as Reuters reports, "While more than 46 million people worldwide have been infected with COVID-19, confirmed cases of re-infection are so far very rare."
The CDC says that based on what we know from similar viruses, some reinfections are "to be expected", but they're still trying to learn more about when and how often it happens. "We just don't have enough data to be making any definitive claims yet," Dr. Rivera says.
Worth noting: No one's born with any kind of immunity to COVID-19. "We refer to this as novel coronavirus because nobody has natural immunity to it," Dr. Rivera says. "It's a brand new virus from the coronavirus family." This also means that exposure to other coronaviruses (not from COVID-19) wouldn't offer any kind of cross-immunity, she says.
Of course, not getting a straight answer on our COVID-19 questions can be frustrating. But when it comes to immunity, there's a reason the experts are being so cautious. They don't want to give a blanket answer before they are reasonably certain that they're right — because if they tell recovered people that they're immune, many of those people could start participating in activities that we know promote the spread of the virus, and if it turns out that even a small percentage of those people can get reinfected, we'd be looking at another spike.
The good news is, scientists are discovering new information about how this coronavirus behaves and how our bodies react to it every day. But for now, the same rules apply. Wear a mask, wash your hands, and physically distance. One thing we can say for sure is that these simple measures really make a difference in slowing the spread and keeping your community safe.