The only benefit of dealing with COVID-19 is the reassurance that you probably won’t have to relive the virus anytime soon. But how long COVID antibodies last has been a matter of debate for some time.
“We don’t know exactly,” says William Schaffner, MD, an infectious disease specialist and professor of medicine at Vanderbilt University School of Medicine in Nashville. “It’s partly because COVID has complicated things for us by coming up with new variants that are a bit different from the previous variants that exist.”
Thomas Russo, MD, professor and chief of infectious diseases at the University at Buffalo in New York, agrees. “Our data is somewhat imperfect,” he says. “The studies come out and the variants stay ahead of our clinical data to some extent.”
However, a recent large study published in The Lancet suggests you may enjoy longer protection against COVID-19 infection than experts previously thought. What can happen from person to person, however, is a bit complicated. Here’s what you need to know about how long COVID immunity lasts and why doctors still recommend getting vaccinated if you’ve had the virus.
How long does natural immunity last after COVID-19?
Again, it can be difficult to say for sure how long your natural immunity will last after you get COVID-19 since the variants keep changing and everyone’s immune system is different. However, some data suggests that you can expect protection for some time.
In general, natural immunity after COVID-19 appears to last at least six months after being infected, according to the Centers for Disease Control and Prevention (CDC).
A new study published in The Lancet found that the immunity you get from being infected with COVID-19 is as protective as vaccination against severe illness and death. The study, which is the largest meta-analysis to date on immunity after having COVID-19, analyzed data from 65 studies from 19 countries and compared the risk of people getting the virus again. who had just relied on those who hadn’t been infected with it. (Note: New Omicron subvariants such as BQ.1 and currently circulating subvariants were not part of the study.)
Researchers found that having COVID-19 reduced a person’s risk of being hospitalized and dying from COVID reinfection by 88% for at least 10 months.
However, people could still be reinfected with the virus (especially a subvariant of Omicron), indicating that while protection against hospitalization and death remained high during the study period, protection against the symptoms of the virus fades faster.
Having had COVID-19 before the Omicron variants emerged didn’t seem to help much. People who had already been infected with a different variant had a 74% chance of being protected from reinfection after one month, but this fell to 36% by 10 months.
How long does vaccine-induced immunity last?
It’s not entirely clear. The CDC is a bit vague about this, saying online that it’s still under review. However, data published in The New England Journal of Medicine says you can expect at least six months of protection after being vaccinated, and that’s what doctors usually advise patients too.
“It’s going to vary depending on who you are and how strong your immune system is – the same considerations apply as for a previous infection,” says Dr Schaffner. However, he says, there is some data to suggest that people who are older or have weakened immune systems will see their immunity decline after four to six months. “That doesn’t mean it drops to zero, though,” he says.
Dr. Schaffner also points out: “The data indicates that people who are up to date with their vaccinations have a much lower risk of hospitalization than partially vaccinated or unvaccinated people. If you are not vaccinated at all, your risk of hospitalization is about 12 to 15 times higher than for vaccinated people.
Note: the recent Lancet One study found that vaccination generally provided the same level of protection against reinfection as a previous infection. However, it only looked at people who had received two doses of the mRNA vaccine, not three, four or the bivalent booster.
Do subvariants of COVID-19 evade immunity?
From now on, no. However, the newer variants in circulation seem to be quite good at evading immunity. “XBB.1.5 is extraordinarily immuno-evasive,” says Dr. Russo. In fact, the World Health Organization (WHO) calls XBB variants “the most antibody-resistant variants to date.”
Still, “all variants are subject to some degree of vaccine protection at this time,” says Dr. Schaffner.
Why booster shots are important for immunity
Importantly, this is a “controversial topic” even among infectious disease physicians, says Liam Sullivan, DO, infectious disease physician at Corewell Health. Some believe a bivalent booster is not necessary for people under 50 who are in good health, he points out, noting that the evidence is ‘limited’ that a booster shot will help fully vaccinated people and healthy. “If you’re young and healthy, and you’ve had an infection in the past 12 months, you probably don’t need it – the infection probably served as a booster,” he says .
But the CDC says it’s a good idea to get a booster three months after being infected in order to get maximum protection in the future. Research also found that people who were infected and then vaccinated (or vice versa) have the best protection against COVID-19 within a few months.
Also, immunity fades over time, and it’s better to develop it from a vaccine than from an infection, says Dr. Russo. “If you rely on immunity from a previous infection, you run the risk of dying or having long-term health consequences,” he points out.
What is Hybrid Immunity?
You may have heard the term “hybrid immunity” at some point. This “refers to when you were vaccinated and infected – either vaccinated first and infected next, or infected first and vaccinated afterwards,” says Dr. Sullivan.
People who have hybrid immunity “probably have the best form of immunity rather than people who have just been infected or vaccinated,” Dr. Sullivan says. But, he adds, “I wouldn’t encourage people to go out and try to get infected.”
Dr. Russo agrees. “If you’ve been infected and want to maximize your protection and minimize the risk of having a bad outcome, getting the bivalent booster is your best strategy right now,” he says.
Overall, Dr. Sullivan recommends people keep in mind that there is still a lot of research being done with COVID-19. “There is still a lot to discover and there is a lot of gray,” he says. “It’s going to take a lot of study and time until we have more information. People shouldn’t be shocked if this information changes.
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