If You’ve Had COVID-19, Do You Still Need the Vaccine?
If you had COVID-19 and recovered, should you still get vaccinated? Here's what to know about your post-infection immunity to coronavirus and the risk of possible reinfection.
Should you get the vaccine if you’ve had COVID-19?
Emergency department physician Laurence Degelsmith, MD, of Northern Westchester Hospital in Mount Kisco, New York got his first COVID-19 vaccine in December.
Two days later, he was tested for COVID-19 at work and it was positive, although he only had minor COVID symptoms.
“I was cleared for work January 3, ten days after a positive test but likely 14 to 17 days after actually getting COVID,” he says. He received his second dose of the Pfizer vaccine on schedule on January 10, three weeks after the first dose.
So why did Dr. Degelsmith go ahead with the second dose if he’d just had COVID?
“It is important to receive the second vaccine three weeks after the first for Pfizer and four weeks for Moderna—there is no information that I could find to alter that recommendation even if diagnosed with COVID after the first dose,” says Dr. Degelsmith. But, “I would not have received my first dose if I was diagnosed with COVID right before,” he says.
Many people who’ve already had COVID are wondering if or when they need to be vaccinated, since they may have some natural immunity triggered by the presence of the virus when they were infected.
In cases like Dr. Degelsmith’s, the timing can be complicated if you’re diagnosed right before or after your first shot, or any time in between doses.
So what guidelines should you follow if you’ve already been sick? We asked some experts for their recommendations about the new COVID-19 vaccines.
All advice is current as of this writing, but keep in mind that knowledge is changing rapidly as scientists gather more information—make sure you’re looking at the most up-to-date info.
What is natural immunity to COVID-19, and how long does it last?
When you get the SARS-CoV-2 virus, which causes COVID-19, your immune system creates “search and destroy” antibodies that can recognize the virus and better resist it next time.
“Natural infection with COVID-19 does induce some antibody, but the level of antibody seems to be below that which is necessary to keep you from getting reinfection,” says Don Middleton, MD, vice president of family medicine at the University of Pittsburgh. Although uncommon, we do know that coronavirus reinfection is possible.
These natural COVID-19 antibodies don’t stick around forever and doctors aren’t sure how long they will protect you.
“One major gap in knowledge with respect to COVID-19 is how long immunity lasts after infection,” says Michael Chang, MD, an assistant professor of pediatric infectious disease at McGovern Medical School at UTHealth in Houston. “There have been some mixed reports about how long immunity lasts, but it depends on how the various publications are measuring ‘immunity.’ Mixed results anywhere from weeks to months have been reported for detectable antibody levels,” he says.
How does vaccine immunity work?
Vaccines basically try to replicate this process in a way that allows you to escape a true first-time encounter with a potentially deadly germ. “Basically a targeted foreign substance is injected into a person, and cells called lymphocytes are responsible for making antibodies to that foreign substance to get rid of it,” Dr. Middleton says. “That process takes some time, usually 10 days to reach levels that are protective,” he explains.
In the Pfizer and Moderna COVID-19 vaccines, messenger RNA is used to deliver the information about the virus to the body’s cells; the upcoming Johnson & Johnson vaccine uses a harmless form of an adenovirus (a cold virus) to deliver that information.
Vaccines aim to mimic the body’s natural response, so it might not be exactly the same. But, “if a well-designed vaccine can activate the immune system ‘enough’ and in the right ways, vaccine immunity can be effective in minimizing risk of serious infection,” Dr. Chang says.
The creation of antibodies sometimes causes a low fever or other typically mild side effects, but the vaccine can’t actually give you the disease. “The initial response to a vaccine is usually quite robust with high levels of antibody, but once the foreign substance is no longer present, the level of antibody decreases to a plateau,” Dr. Middleton says.
How long does the COVID-19 vaccine last?
Some vaccines, like measles and polio, generate high levels of antibodies that stay elevated for years, but how long the COVID-19 vaccine can protect you isn’t yet known.
“No one knows how long antibody induced by the COVID-19 vaccines—either one or two doses of the many possible forms of vaccine that are available now or will shortly be available—will last,” Dr. Middleton says. “Some studies suggest that it lasts for at least three months without falling off [to the plateau level], suggesting that antibody might last for a year or even two,” he says.
The antibody level might not be the whole story, either, as they are not the only way our immune system fights infection.
“The immune system is very complicated—a lower antibody level after one year from vaccine or infection may still confer some or all immunity against further infections, but that remains to be seen,” Dr. Degelsmith says. “I don’t think anyone knows what levels confer immunity and for how long,” he says.
Dr. Middleton says the hope is that even if protection drops, it will at least reduce serious cases that could result in hospitalization or death.
Because the pandemic is only a year old, there simply hasn’t been enough time to study how long vaccine immunity (or natural immunity, for that matter) lasts, Dr. Chang stresses.
He adds, “The true ‘test’ of immunity is to see if or when reinfection in people becomes more common—if that never happens, then we as a community will know that immunity is long-lasting,” he says. “If we start documenting more reinfections in the near future, we will know that immunity doesn’t last as long as we’d like.”
Why is vaccine immunity better than natural immunity?
The COVID-19 vaccine could provide greater protection than the natural immunity triggered by infection with the virus itself.
“Both of the current vaccines produce antibody levels that are higher than the level that follows natural infection, and higher than that necessary to protect you from getting further infections,” Dr. Middleton says.
Plus, COVID-19 vaccine immunity may last longer than natural immunity.
“The experts feel that vaccination offers a more ‘guaranteed’ antibody production to prevent further re-infection for a longer period of time—hopefully, a year or two—instead of several months,” Dr. Degelsmith says. “The data is not out there yet because we’re only 10 or 12 months into this virus, and less time understanding how it survives in the body, so I believe that a lot of information will be coming in the next six months to answer some of these questions,” he says.
Should you wait to get vaccinated if you just had COVID-19?
Timing is everything here, so it really depends on how long ago you had the virus.
“The current recommendation is to wait at least 14 days after a positive test before seeking vaccination,” Dr. Chang says. “This recommendation is primarily to ensure that people who could still be contagious are not going to vaccination sites and potentially spreading the disease.”
This goes for health care workers too, which is why Dr. Degelsmith made sure he was done with his COVID-19 quarantine before getting his second vaccine dose. If, like him, you come down with COVID in between shots, it’s recommended you complete the shots as scheduled, as long as you are out of isolation.
If you are just recovered from COVID-19 and haven’t had your first shot yet, the CDC notes it’s fine, but not required, to wait a few months to let others with no natural protection go first.
“It is OK to wait 90 days after infection if desired because one will likely have immunity for that time period anyway after infection,” Dr. Degelsmith says.
Dr. Chang agrees, but urges caution. “As it appears there is some immunity, i.e. less risk of reinfections, in the first few months following natural infection, in the setting of low [vaccine] supply, people with recent infection may choose to temporarily delay vaccination,” he says. “However, again with no clear cutoff for when natural immunity wears off, it’s difficult to know exactly when the ‘right’ time is,” he says.
If you tested positive but were asymptomatic, vaccination is still important when you’re cleared from quarantine. “Both asymptomatic and symptomatic persons benefit from vaccination,” Dr. Middleton says. In fact, it might even be more important to get vaccinated if you had few symptoms.
“It is felt that mild or asymptomatic infections may not build up significant antibody protection to prevent recurrent infections in some people; or, the immunity after infection may not last more than several months,” Dr. Degelsmith says.
Should get vaccinated even if you had COVID-19 to ward away new variants?
This is definitely a consideration and a possible reason not to wait to get vaccinated after you’ve recovered from COVID-19, because you might not have as much natural protection against reinfection from mutated forms of the virus.
“A further monkey wrench is that the current new variants—three are now known from England, Brazil, and South Africa, but the potential number is limitless—may not be totally controlled by antibody levels that do protect you from the initial strain,” Dr. Middleton says. “Antibodies must fit like a glove on the hand—if the first form of COVID-19 was shaped like a right hand but the new variant of COVID-19 is shaped like the left hand, antibodies shaped like right-handed gloves will not work as well trying to cover left hands,” he says.
Dr. Chang uses another metaphor, a lock and key, to describe how antibodies search out and lock into their target; if the “lock” appears differently, they can’t recognize it.
“So there is significant concern that neither existing immunity from natural infection of the initial strain, nor immunity from the current vaccinations may protect against reinfection from the new variants,” he says.
But, “there are some very preliminary (non-peer-reviewed) laboratory data that suggests at least for the current U.K. variant, both the Pfizer and Moderna vaccines will still be effective, but no clinical data to draw any conclusions,” Dr. Chang says. Scientists think antibody levels for Moderna and Pfizer will also be protective against the South African variant, he says, but again, more clinical data is needed. No data exists yet for the Brazilian variant either. The vaccines may also be adjusted to better match the new variants, according to the BMJ.
In short, “it is possible that the variants may make reinfection more likely,” Dr. Chang says, but we don’t have solid numbers on the chances of that yet. Even so, vaccination is still important because the more people who are vaccinated, the less virus there will be to replicate. This means fewer future mutations.
Is getting vaccinated after COVID-19 ineffective or harmful?
No, this is not the case. “There is no known information that suggests the vaccine will be less effective if you have been recently infected with COVID-19,” Dr. Chang says. If anything, the vaccine could give you an extra boost.
“Getting vaccinated while having Covid or while recovering from COVID is not likely going to cause any harm because the CDC knows that many volunteers who were vaccinated during the trials probably had undetected Covid infection, and there were no significant problems during the studies,” Dr. Degelsmith says. “Potentially it will confer a longer immunity. I feel that the more antibodies, the better,” he says. But, he notes a lack of data on that point.
Dr. Chang also echoes that getting vaccinated after having COVID is not harmful.
“There were no documented serious adverse events related to vaccination in patients who had evidence of prior COVID infection in the Moderna or Pfizer trials,” he says. Plus, “since there is still uncertainty of how long immunity lasts after ‘wild-type’ [natural] SARS-CoV-2 infection, it is a reasonable conclusion that boosting your immune response after natural infection with a COVID-19 vaccine would likely add additional protection,” he explains.
Is there anyone who shouldn’t get vaccinated after COVID-19?
The CDC does note that if you had COVID-19 and received treatment with monoclonal antibodies or convalescent plasma (antibodies collected from people who’ve had COVID-19 and used to treat other people), you should hold off for 90 days before getting the vaccine to be certain it will be effective.
These treatments haven’t been studied with the vaccine, so you should delay in order to avoid potential interference of the therapies with vaccine responses.
Some people with certain conditions that make them more likely to have COVID-19 may have less protection from the vaccine. This just makes it more important to get the shot.
“In some individuals, especially those who are older or who have an underlying disease like cancer, antibody levels following either dose of vaccine may be below the level that provides protection, so it is possible to develop COVID-19 infection,” Dr. Middleton says. Still, some protection is better than none.
Why might people who had COVID-19 have stronger immune reactions to the vaccine?
Anecdotally and in not yet peer-reviewed research, some people who previously had COVID-19 had a strong immune reaction to the first dose of the vaccine, according to a recent study in medRxiv. This is compared to those who hadn’t had COVID-19, who had a stronger reaction to the second dose.
“Researchers suggest that in patients with previous infection, a strong antibody response was noted following a single dose of vaccine,” Dr. Chang says. In addition, they had more immune symptoms such as fatigue, headache, fever, and chills. The findings suggest that people with a past COVID-19 infection might need only one dose of the vaccine, which would free up more of it for people who need two doses.
Dr. Degelsmith was told he might have more vaccine side effects with his second shot due to his recent infection with COVID-19 but he did not, he says. “It may turn out that the second dose is unnecessary if one gets COVID infection after the first dose, but we don’t have that answer yet,” he says.
The available research is not yet strong enough for guidelines to reduce vaccines to a single shot. “This report had only 109 people, only 68 of whom had prior infection, not the thousands or millions needed to be closer to the truth,” Dr. Middleton says. “So I would state that some people with prior infection may have a higher rate of headache and chills and fatigue with the vaccine,” he adds.
“A second dose is still recommended under the EUA [emergency use authorization]. I trust that CDC/FDA will change the advice with more information,” he says. But, Dr. Middleton says that waiting 90 days after an infection may reduce the chances of strong immune symptoms after vaccination.
Again, more information is needed, so it’s important to stick to the current guidelines for the two-dose schedule for now. What’s certain is the vaccines are safe and effective, and important for everyone to get to stop this virus, whether you’ve already had COVID or not.
- Laurence Degelsmith, MD, Emergency Department physician, Northern Westchester Hospital, Northwell Health
- Centers for Disease Control and Prevention: “Interim Clinical Considerations for Use of mRNA COVID-19 Vaccines Currently Authorized in the United States”
- Don Middleton, MD, vice president of Family Medicine at University of Pittsburgh
- Michael Chang, MD, assistant professor of pediatric infectious disease, McGovern Medical School at UTHealth
- Science: “Robust neutralizing antibodies to SARS-CoV-2 infection persist for months”
- Centers for Disease Control and Prevention: “Understanding mRNA COVID-19 Vaccines”
- Centers for Disease Control and Prevention: “Frequently Asked Questions about COVID-19 Vaccination”
- JAMA: “SARS-CoV-2 Vaccines and the Growing Threat of Viral Variants”
- bioRxiv: “SARS-CoV-2 501Y.V2 escapes neutralization by South African COVID-19 donor plasma”
- bioRxiv: “Neutralization of SARS-CoV-2 lineage B.1.1.7 pseudovirus by BNT162b2 vaccine-elicited human sera”
- bioRxiv: “mRNA-1273 vaccine induces neutralizing antibodies against spike mutants from global SARS-CoV-2 variants”
- Genomic Epidemiology: “Genomic characterisation of an emergent SARS-CoV-2 lineage in Manaus: preliminary findings”
- BMJ: “Covid-19: Moderna plans booster doses to counter variants”
- New England Journal of Medicine: “Covid-19 Vaccine — Frequently Asked Questions”
- New England Journal of Medicine: “Efficacy and Safety of the mRNA-1273 SARS-CoV-2 Vaccine”
- New England Journal of Medicine: “Safety and Efficacy of the BNT162b2 mRNA Covid-19 Vaccine”
- medRxiv: “Robust spike antibody responses and increased reactogenicity in seropositive individuals after a single dose of SARS-CoV-2 mRNA vaccine”