(CNN) – When a person gets COVID-19, it’s likely they’ll also get some degree of immunity after recovering.
But researchers still don’t know for how long.
“Reinfection can and does occur with COVID-19, though it appears to be a rare occurrence so far,” according to emergency physician Dr. Leana Wen.
Of the many millions of COVID-19 cases around the world, only a handful of documented cases show re-infection.
But it’s still a concern.
“The virus that causes COVID-19 is a coronavirus and coronaviruses cause illnesses like the common cold that are known to re-infect people year after year,” Wen said.
So far, research has shown that any immunity gained after COVID recovery will most likely last for months, not years.
“We also don’t know how complete the protection is, and whether, if you’re exposed, you may not get sick but could still transmit the virus to others,” according to Wen.
That’s one reason she says the herd immunity approach to COVID-19 doesn’t work.
If we let the virus infect most of the population, it’s estimated that millions of people could die without any guarantee that those who survive will be protected for longer than a matter of months.
“That’s why prevention is so critical,” Wen said. “It’s really important that we do everything we can to protect from getting coronavirus.”
Since coronavirus vaccines are still being developed, we don’t know what reinfection means for the vaccine, but it’s likely that a single-dose vaccine won’t be enough.
Ultimately, we might need booster shots like get for tetanus, or even annual shots like we do for the flu.