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  • New research finds that a major immune response occurs if a person has been both vaccinated and developed COVID-19.
  • Researchers found that the order this occurs does not appear to have a major effect on overall immunity to the disease.
  • This hybrid or “super” immunity may help people from developing COVID-19 in the future.

Researchers are still learning how the immune system can fend off the novel coronavirus after vaccination or previous infections.

In a new study, researchers say people with “hybrid immunity” from having been vaccinated and previously having COVID-19 have significant protection against the disease.

The researchers said their findings illustrate the importance of people who’ve had COVID-19 to still get vaccinated.

Research published earlier this year by the Oregon Health and Science University (OHSU) found that a major immune response occurs if a person has been both vaccinated and developed COVID-19.

They found that the order this occurs does not appear to have a major effect on overall immunity to COVID-19.

This new study is slightly different than findings from a previous study released late last year. That study found that experiencing a breakthrough coronavirus infection after vaccination could prompt a very strong immune response that provides a kind of “super immunity” against future infections.

We talked with experts to understand what “super” immunity can look like.

The earlier study included 104 OHSU employees vaccinated with the Pfizer-BioNTech COVID-19 vaccine. They were divided into groups based on COVID-19 history: those who had an infection before or after vaccination, and those who never had an infection.

After controlling for factors that included age, sex, and time between vaccination and contracting an infection, blood was drawn from the participants and exposed to three live variants of the coronavirus.

Researchers found both of the groups with “hybrid immunity” generated higher levels of immunity than the vaccinated group that didn’t get a breakthrough infection.

“Hybrid immunity refers to infection-induced immunity (natural immunity) that is further boosted by vaccination following a natural infection,” Dr. Rafeul Alam, an allergist and immunologist at National Jewish Health, told Healthline.

It’s important to note this study was conducted before the Omicron variant became dominant, but researchers said they expected the hybrid immune responses would be similar for Omicron infection.

According to the Oregon study, it doesn’t matter whether someone gets a breakthrough infection or is vaccinated after natural infection.

The immune response measured in blood serum in people, who had both vaccination and a COVID-19 case, had antibodies that were equally abundant and at least 10 times more potent than immunity developed from vaccination alone.

“The finding that breakthrough infection really boosts immunity was not surprising,” said Dr. Bill Messer, senior co-author of the study.

“Our prior work has shown that the vaccine does a great job priming the immune system, and I expected it to have a robust response to a breakthrough infection,” he continued.

According to Messer, while he was a “bit more uncertain” about natural infection than vaccination, since natural infection produces “variable immunity,” the principle is the same.

“The first dose or infection gives rise to immune cells that are poised to rapidly expand if they are stimulated again, much as the vaccine does,” he said.

According to Dr. Robert G. Lahita, director of the Institute for Autoimmune and Rheumatic Disease at Saint Joseph Health and author of “Immunity Strong,” vaccines aren’t “100 percent guarantees” you won’t contract an infection.

“Rather, vaccines help to keep you out of the hospital and/or at risk of dying from getting a severe case of the virus,” he said.

Lahita also warned against purposefully infecting yourself with the coronavirus to achieve a better immune response.

“You should not under any circumstances try to contract COVID, because you may very well end up with long COVID symptoms like brain fog, mobility issues, heart damage, lung damage, and loss of taste and smell that can last 6 or more months or be permanent,” he cautioned.

Eric Maroyka, PharmD, BCPS, a senior director at American Society of Health-System Pharmacists (ASHP) Center on Pharmacy Practice Advancement, said breakthrough infections might happen for several reasons.

These include waning immunity from initial vaccination or infection, inadequate immune response from initial vaccination or infection, or mutation in the virus that evades current antibodies.

“Inadequate immune response occurs in people who have defects in their immune system that occur naturally or are a result of suffering from certain diseases or taking medications that interfere or impair the immune system,” he continued.

Maroyka said examples include people with cancer and people who take medications such as steroids that interfere or block the body’s immune response.

Alam explained that the combined effect of natural and vaccine-acquired immunity is “synergistic,” meaning they amplify each other.

“If the protection from natural and vaccine-elicited immunity each lasts 6 months, then the protection from herd immunity should last longer than 12 months, likely 15 to 18 months or longer,” he said.

Dr. Nikhil Bhayani, FIDSA, infectious disease specialist at Texas Health Resources, emphasized the importance of vaccination even after coronavirus infection.

“Since we do not know precisely how long people are naturally protected from getting COVID-19 again after clearing an infection, COVID-19 vaccinations are recommended, even for those who have recovered from the disease,” he said.

“COVID-19 vaccine, current and future, hopefully superior vaccines, will continue to have a role even when COVID-19 becomes endemic,” said Alam.

He added that two major challenges to the current vaccine approach must be addressed to beat COVID-19: the limited duration of neutralizing antibodies from vaccination and the virus’s ability to evade these antibodies through mutation.

“The existing and emerging technologies can address these challenges, but will need some time,” said Alam.

Maroyka pointed out that getting vaccinated is the best way to mitigate COVID-19 transmission and prevent infection.

“If we look at diseases such as polio, smallpox, diphtheria, pertussis, they are controlled or eliminated because of effective vaccines,” he said. “Similarly, this likely will be the story with the COVID-19 vaccines.”

New research finds that having COVID-19 before vaccination or getting a breakthrough infection after vaccination both provide a type of “super immunity” to future infection.

Experts warn this doesn’t mean people should purposefully try to infect themselves with the coronavirus to achieve greater protection against COVID-19, since there are serious health risks involved.

They also say vaccination will play an important role even after COVID-19 becomes endemic.