Although it’s been around for nearly a year now, we’re still learning quite a bit about coronavirus. From prevention and treatment to the prevalence of asymptomatic cases, there are still quite a few lingering questions about the virus—including exactly how immunity works.

More specifically, can you get COVID twice? For many people who survive the virus, they’re comforted by the idea that they can no longer get it and hopefully can’t give it to others, either. But how much truth is there to this? We asked doctors—here’s what they had to say.

Can you get COVID twice?

The short answer to this question? Yes, you can get COVID twice—but it’s not very likely. “There haven’t been large, well-controlled studies done on this, but it appears to be very rare and uncommon. It will be interesting when we can all slow down enough and study this,” says Dr. Alan Taege, an infectious disease doctor at the Cleveland Clinic.

The reasons why people may get COVID-19 twice are still unclear, but Dr. Taege has a few guesses. “They may have encountered a slightly different virus, but the good news is that the second time they acquired it, they had a milder form, which says the immune system can still recognize it. This is what we expect or hope out of a vaccine, that the immune system will recognize it well enough so it doesn’t cause serious disease.”

Another possibility? Immunity might not last that long. “From the cases we’ve seen, it’s not clear if their immunity didn’t last long enough to protect them from a second infection, or if people did not develop immunity from the first infection,” notes Dr. Julita Mir, Infectious Disease Physician and Chief Medical Officer of Community Care Cooperative.

So, How Much Longer Will We Have to Wear Masks?

Beware of a positive COVID test that stays that way

COVID tests are getting better and better, but they’re not perfect. And while antigen tests (also known as rapid tests) can produce false negatives, PCR tests (nasal swab tests) are more sensitive and may not be able to distinguish a live virus from a dead one. If, for example, you test positive for the virus and then get tested again in a few weeks once you’re symptom-free, a positive result doesn’t mean you got COVID again. It’s much more likely that the virus is dead and that you’re no longer contagious to others, but that it simply hasn’t cleared your system yet.

According to the CDC, people can test positive for up to three months following infection. Once you’ve isolated for 10 days or more and no longer have symptoms, you are not considered contagious to others, regardless of the result a PCR test might produce.

Is it possible to get COVID and not build antibodies?

According to Dr. Taege, getting COVID-19 and not having the antibodies to show for it probably won’t happen, although there are different levels of antibodies. Someone with a mild case might produce fewer antibodies than someone with a more severe case, for example, but even low levels of antibodies tend to be enough to fight off the virus.

Dr. Mir adds that immunity is complicated, and there’s more to the picture than antibodies alone. “Interesting, some patients may not have detectable antibodies but still be protected,” she explains. “There are still a lot of questions around this, and we’ll need more research and more time to answer them.”

While getting COVID twice seems to be rare at this point, it’s not impossible—and for this reason, it’s still important to get the vaccine even if you’ve already had coronavirus.

“Compare it to the shingles vaccine. People get a shingles vaccine even though they’ve had chicken pox and have had it in the past,” says. Dr. Taege. “The purpose is to heighten the immunity and decrease the chances of developing disease. People who have had COVID still should be immunized somewhere down the road, although currently it is being suggested that those who have had it should wait and allow people who have not had it to get the vaccine first.”

Next up, find out whether or not COVID vaccines will be free, plus the answers to all your other pressing vaccine questions.