‘Natural immunity’ after COVID infection might not last as long as you think. Here’s why

Cases of people testing positive for COVID-19 after having had the virus previously, including among some folks who also got vaccinated, have raised questions about how much immunity people get from infections.

For most people, the body’s immune system creates antibodies once you get the virus that helps prevent you from getting it again, experts say. But that immunity doesn’t last forever, and it doesn’t always protect against new virus variants.

Here’s what to know about the immunity you get from having had COVID-19, how long it lasts and what those who’ve had COVID-19 should do about vaccines.

Does getting COVID make you immune to COVID?

Getting COVID-19 can trigger some “natural immunity” to the virus, according to researchers with the Johns Hopkins School of Medicine.

“Natural immunity is the antibody protection your body creates against a germ once you’ve been infected with it. Natural immunity varies according to the person and the germ,” Drs. Lisa Maragakis and Gabor Kelen wrote in a piece published by their university.

Levels of natural immunity vary from person to person, they said, and “a mild case of an illness may not result in strong natural immunity.”

How long does ‘natural immunity’ to COVID last?

Although natural immunity can provide some protection, it doesn’t last forever, Maragakis and Kelen added.

“New studies show that natural immunity to the coronavirus weakens (wanes) over time, and does so faster than immunity provided by COVID-19 vaccination,” they said in their article.

Scientists are still working to learn more about how long antibodies produced by a COVID-19 infection, and vaccination, last, researchers with the University of South Carolina’s School of Medicine say.

“This is a challenging question because the virus is relatively new and novel variants have continuously emerged,” researchers Prakash Nagarkatti and Mitzi Nagarkatti wrote in an article published by their university.

“While it is becoming clear that some form of immune response against the virus can be detected for more than a year after COVID-19 infection, their levels may not be enough to provide full protection against reinfection,” they continued.

Should you get the COVID vaccine if you’ve had COVID?

Even if you’ve had COVID-19 and therefore may have some antibodies in your system, it’s still worthwhile to get vaccinated against the virus, the Centers for Disease Control and Prevention recommends.

“Getting a COVID-19 vaccine after you recover from COVID-19 infection provides added protection against COVID-19,” the agency says. “People who already had COVID-19 and do not get vaccinated after their recovery are more likely to get COVID-19 again than those who get vaccinated after their recovery.”

The CDC also encourages everyone who is eligible to keep up with booster shots, to help account for “decreases in the protection COVID-19 vaccines provide over time.”

New COVID subvariants may escape antibodies, though vaccines provide some protection

New variants of COVID-19 continue to be detected, including the BA.4 and BA.5 “sub-variants” of the Omicron variant, which the CDC estimates now account for more than 20% of new cases nationwide.

And, researchers say, these new variants may be able to “escape” antibodies triggered by previous COVID-19 infections and vaccination.

A study by the Imperial College London indicated that people infected with the omicron variant “show poor immunity boosting against future covid-19 infection.”

Omicron is “an especially stealthy immune evader,” said Danny Altmann, study co-author from Imperial College London, told the British Medical Journal. “Not only can it break through vaccine defenses, it looks to leave very few of the hallmarks we’d expect on the immune system,” he said. “It’s more stealthy than previous variants and flies under the radar, so the immune system is unable to remember it.”

New variants may mean more “breakthrough infections,” the CDC says, but that doesn’t mean vaccines can’t help.

“Breakthrough infections in people who are vaccinated are expected,” the agency says, “but being up to date on recommended vaccines is effective at preventing severe illness, hospitalizations, and death.”