If you already had COVID-19, you might be wondering if you should plan to get vaccinated.
Doctors are still looking into how long immunity from natural infection with the coronavirus lasts, but the current thinking is that antibody levels begin to drop after a few months ― particularly in asymptomatic and milder cases ― eventually leaving people susceptible to catching the virus a second time.
Though this particular issue needs more research, health experts suspect that people with a recent COVID-19 infection may be able to hold off a few months before getting the vaccine. Those who have been recovered from COVID-19 for several months, however, should plan to get the shot as soon as it becomes available to them.
Here’s why, along with some other information you need to know:
You’re probably protected for a few months after a COVID-19 infection.
Onyema Ogbuagu, an infectious disease doctor at Yale Medicine who has been testing the Pfizer vaccine, believes people who were recently infected probably don’t need to get the shot right away.
Studies have found that neutralizing antibodies produced by natural infections last, at the very least, for a few months. In cases of reinfection, the second illness typically doesn’t occur until three to four months after the first.
“It’s pretty certain, although you can never say confidently, that in the first few months after infection … the risk of reinfection is really low,” Ogbuagu said.
If you had COVID-19 several months ago, however, that might be a different story.
It’s generally believed that natural immunity from COVID-19 drops after a few months, though evidence has been mixed. We also know that antibody levels from other common coronaviruses wane rapidly, and the same could be true with COVID-19, according to Otto Yang, a professor of medicine in the division of infectious diseases and of microbiology, immunology and molecular genetics at the David Geffen School of Medicine at UCLA.
“People probably will become re-infectable based on antibodies dropping when people have been naturally infected. We don’t know what the timing is going to be, though, like how soon they become susceptible to reinfection,” Yang said.
Ogbuagu said he would recommend the vaccine for someone who had COVID-19 three to four months ago (or longer), especially if it was a milder case. Evidence suggests that those who had a more serious go of it may emerge with more durable protection that could last for several months.
Researchers currently suspect that immunity conferred by the vaccine will be more robust than immunity achieved from natural disease. This theory is still being tested, Ogbuagu said, and regardless of whether you had a mild or severe case, you’ll want to get the shot at some point.
Could there be risks to getting the vaccine if you already had COVID-19?
There isn’t much research on how previously infected patients respond to the coronavirus vaccine.
According to Ogbuagu, vaccine clinical trials only recently started focusing on participants who’d had COVID-19 to learn more about the body’s response to vaccination where there had already been an immune response.
People who’d previously been infected with COVID-19 were not intentionally included in the Pfizer trial that Ogbuagu worked on. But during the trial, the researchers identified a number of participants who already had neutralizing antibodies, suggesting that they had been infected.
The good news is that the Pfizer vaccine was just as safe in people with neutralizing antibodies as it was in people with no neutralizing antibodies, Ogbuagu noted.
That said, more data is needed to determine if this will always be true.
One theory is that the vaccine could increase antibody levels in people who’ve already been infected, essentially working like a booster shot. But there’s also a chance ― at least, “a theoretical possibility,” Ogbuagu said ― that vaccination on top of natural immunity could lead to a severe reaction in certain people.
Yang isn’t too concerned. “There’s no reason to think there would be an increased risk, so they might as well get vaccinated,” he said. There are plenty of cases where people have safely been vaccinated after having a particular disease — like the flu, polio or chickenpox and the shingles shot.
As more data becomes available, we’ll get a more concrete picture of how the coronavirus vaccine behaves in previously infected people with longer-lasting natural immunity.
Should you get an antibody test before the COVID-19 vaccine?
Some doctors have toyed with the idea of conducting antibody tests to determine if someone has natural immunity before administering the vaccine.
At least 16 million Americans have already had COVID-19, and plenty more will likely get it in the weeks and months ahead, so some percentage of the population will be immune when the vaccine becomes available to them. In theory, testing for neutralizing antibodies would identify people with no immunity who could be prioritized for vaccination so we can reach herd immunity faster.
But Ogbuagu said this isn’t a scaleable strategy. Antibody tests can be expensive. They’re also not foolproof and occasionally lead to false negatives and false positives. And uncertainty remains regarding what exactly antibody levels tell us about protection.
Because of these issues, Ogbuagu suggests antibody testing wouldn’t be necessary unless researchers found out there was a real risk in vaccinating previously infected people (which, again, is very unlikely but cannot be ruled out just yet).
The bottom line: The safest bet is to get the vaccine as planned when it’s your turn ― unless you’ve very recently recovered from COVID-19. In the latter case, you can likely hold off for a couple of months and then step in line to get the shot.
Experts are still learning about COVID-19. The information in this story is what was known or available as of publication, but guidance can change as scientists discover more about the virus. Please check the Centers for Disease Control and Prevention for the most updated recommendations.