Recovered From COVID-19? Here's Why You Should Get Vaccinated Anyway

If you’ve been infected with COVID-19 and recovered from the illness, your immune response may not be strong enough to protect you from future infection. Experts say vaccines likely provide stronger, longer-lasting immunity.

People who recover from COVID-19 carry neutralizing antibodies that may protect them from reinfection. Recent studies indicate that this period of protection may last three months after infection. The Centers for Disease Control and Prevention (CDC) currently says that people who have recovered should have access to the COVID-19 vaccine and that they may delay vaccination for 90 days after the initial infection.

But the scientific community has not yet reached a consensus on how long a person retains immunity from the disease after infection. According to Shiv Pillai, MD, PhD, director of Harvard’s Master of Medical Sciences in Immunology program, the longevity of immunity may depend on the severity of a person’s illness.

“The levels of antibodies are really low in people who have mild disease,” Pillai tells Verywell. “So even assuming that you are protected—you may have some antibodies for 90 days, but the levels are not very high.”

Bolstering Immunity During Infection

When a person is infected with COVID-19, their body creates antibodies to defend against the virus. B-cells within the body produce neutralizing antibodies while killer T-cells recognize and attack the virus. When the infection has subsided, these cells continue to remember the virus so that the immune response is more effective in case of reinfection.

The severity of illness is largely due to the body’s immune response to the virus. If the viral load is smaller, a person’s immune response will be lower, and the resulting antibodies will be lesser. Over time, antibody levels decline and immunity fades.

Some people may be infected with enough of the virus to test positive on a COVID-19 test, but not enough to trigger a strong immune response. These asymptomatic carriers, though infected with the virus, will not likely create enough antibodies to protect against another infection months in the future, Pillai says.

For some diseases, like mumps and measles, these memory cells can provide immune protection for a person’s lifetime after recovery. By contrast, a study in Emerging Infectious Diseases shows that for people who have recovered from SARS, antibodies largely disappear within three years of infection. Pillai says that the durability of the immune response to COVID-19 may be similarly short.

COVID-19 appears to cause such damage to the body that the body’s ability to produce effective B-cells and antibodies may be inhibited. Pillai co-authored a study published in October that analyzed the germinal centers in the lymph nodes of people who died after a COVID-19 infection. It's within these germinal centers that B-cells mutate to become stronger and longer-lived. The researchers found a lack of germinal centers in people who had severe COVID-19 illness, suggesting people may only produce antibodies for a short amount of time after infection.

“If you are very sick, the virus does a number on you,” Pillai says. “The virus not only inhibits your ability to create a good, adaptive immune response—it makes it very difficult to make the best-quality antibodies and the antibodies that will last for a very long time.”

Some evidence on the effect of the virus on the immune response is conflicting. Another study provides evidence that B-cell mutations are actually higher six months after infection, suggesting that long-lived B-cells develop gradually and may provide longer immunity.

Not Worth the Risk

The strength and longevity of people’s immune response to a natural COVID-19 infection vary depending on the viral load, dysfunction of the immune system, and possibly other factors. The approved COVID-19 vaccines, on the other hand, deliver a predictable immune boost.

Studies from Moderna and Pfizer-BioNTech on their approved vaccines do not include data on vaccine benefits or dangers for people who have recovered from the disease. Researchers will likely learn more about the vaccines’ effects and efficacy in the coming months.

COVID-19 reinfections are thought to be relatively rare. Though researchers don’t yet know the likelihood and probable severity of reinfection, studies show that it is possible.

“Reinfection has been demonstrated—it’s not like it is zero,” Pillai says. “So why would you take that risk?”

Impact on Vaccine Distribution

Krutika Kuppalli, MD, an assistant professor of medicine at the Medical University of South Carolina, tells Verywell that in her experience distributing COVID-19 vaccinations, people are not asked whether they have been previously infected. The goal, she says, is to distribute the vaccine to everyone who wants it to ensure full protection.

“One thing we put out in our messaging is…consider waiting 90 days after infection to give other people who haven’t had COVID-19 a chance to get immunity from the vaccine,” Kuppalli says. “But we’re not policing it.”

Even if public health officials intend to prioritize vaccine distribution to people who have not been previously infected, it may be difficult to do so. In order for clinicians to know who has adequate levels of immunity, they would have to receive an antibody test, which could be time and resource-consuming.

“If they had very mild COVID-19, I would treat them like they had no disease," Pillai says. "But if they had serious disease and required hospitalization or were sick for ten days and were very ill, that’s enough—they probably have some immunity and could wait a little bit. But I wouldn’t make anyone wait if the vaccine was widely available.”

The information in this article is current as of the date listed, which means newer information may be available when you read this. For the most recent updates on COVID-19, visit our coronavirus news page.