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How long are you protected against COVID after infection?

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If you’ve recently recovered from COVID-19, you’re probably wondering how long you’ll be immune to infection. As we continue to navigate how to manage new variants and stay safe through the pandemic, it’s important to understand how immunity works.

There are different types of immunity: infection-induced, vaccine-induced, and hybrid (a combination of the two) immunity. We spoke to doctors to learn more about COVID immunity and what to expect after infection. Here’s everything you need to know.

How long does COVID immunity last after infection

Dr. Jason Gallagher, MD, infectious disease expert, clinical professor at Temple University School of Pharmacy and infectious disease clinical pharmacy specialist at Temple University Hospital says “it depends.” It seems that high antibody levels last for at least three months before they start to drop. But when they do drop, they can still be effective, especially against variants similar to those a person has been infected with before. Moreover, antibodies are not the only component of the immune system that helps after an infection, they are only one of them and the easiest to measure.

Some immune responses to the SARS-CoV-2 virus that causes COVID-19 can be detected long after infection – at least a year, Dr. Erica Johnson, MD, Chairman of the Board of Infectious Diseases of the American Board of Internal Medicine, explains. However, this does not mean that you are protected against re-infection for as long, and in fact what we have seen with the omicron line is that many people who have been infected with previous variants or previously vaccinated against COVID-19 are still developed an infection with an omicron subvariant.

This is partly because there are different immune responses to the virus that all play different roles in protecting against future infection, and some parts of that immune response may not be as robust as other parts depending on the person, the nature of their infection. including the variant they were infected with and their history of vaccination and/or infection, adds Dr Johnson.

Related: These are the subtle heart-related symptoms you should get checked out if you have COVID

How does natural immunity work after COVID develops?

After infection, many patients develop antibodies that bind to a specific part of the virus needed for it to infect cells. These antibodies help reduce the risk of reinfection during future exposures to the virus. Other parts of the immune system also mount specific responses to the virus that the immune system can recall upon reexposure to the virus, says Dr. Johnson.

These same types of responses also occur after vaccination and, in fact, vaccination is designed to mimic what would happen if the body were exposed to the virus in the first place.

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How protective is hybrid immunity?

Each time you are exposed to a dose of vaccine or have a natural infection, your immune system remembers its previous exposure to the virus and is strengthened. With the first doses of vaccine alone, this enhanced response in many people would fade after several months. But the combination of being up to date with vaccination and having had a natural infection has been shown to provide a longer-lasting immune response than vaccination alone, says Dr. Johnson.

In fact, a study in the New England Journal of Medicine showed that immunity remained high for more than a year after infection in a study of healthcare workers in the UK who had an infection and two doses of mRNA vaccine.

Related: Here’s What Your COVID Immunity Really Looks Like When You Get That Second Booster

“Hybrid immunity” appears to be the most durable type, but it has the obvious downside that you have to develop COVID-19 before you can get it, says Dr. Gallagher. Either way to catch it, whether it’s getting an infection and then getting vaccinated or getting vaccinated and then infected, seems to work.

This is probably because, until recently, vaccines have only taught our bodies to recognize one type of SARS-CoV-2, and although they have learned this very well (remember that vaccines were over 90% effective in preventing infection), the virus has since changed several times since then. The new bivalent booster vaccines teach immunity against both the “original” SARS-CoV-2 and an omicron strain, and data suggest they protect better against both. Hybrid immunity works the same way, adds Dr. Gallagher.

Additionally, receiving a vaccine after contracting an infection effectively stimulates responses beyond the window offered by the infection.

Next step: Debunking the 10 biggest myths about the COVID vaccine – and no, it won’t give you coronavirus

Sources

  • Dr. Erica Johnson, MD, Chair of the Board of Infectious Diseases of the American Board of Internal Medicine
  • Dr. Jason Gallagher, infectious disease expert, clinical professor at Temple University’s School of Pharmacy and clinical pharmacy specialist in infectious diseases at Temple University Hospital