How COVID-19 hybrid immunity could be a game-changer in a pandemic

As the FDA prepares to decide whether all Americans need booster vaccines, some researchers are reporting preliminary data suggesting that mixing different vaccines could provide even stronger immune boosting.

For now, the data is too scarce to support a mix-and-match strategy, experts say. But scientists are learning more about the strength of the immune response for a person who has already been infected with COVID-19 and then receives the vaccine – a phenomenon called “hybrid immunity.”

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“The best thing we can hope for is that three doses of the vaccine will emulate the super immune response, found among people previously infected with the virus,” said Dr. Paul Goepfert, infectious disease physician and director of Alabama Vaccine. Research Clinic. “This [type of immunity] will protect against variants in the future. “

As the nation continues to fight the pandemic and faces the threat of revolutionary delta variant infections, “superimmunity” is becoming an attractive concept.

In a review recently published in Science, people with this hybrid immunity see an immediate and “striking” improvement in protection – up to a 100-fold increase in their antibody response compared to what they have accumulated afterwards. their infection with COVID-19 – – Dr Shane Crotty, review author and virologist at La Jolla Institute of Immunology, said.

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Experts are also finding that these hybrid antibodies appear to be more versatile and recognize more variants, including those as far apart as the original SARS virus, Crotty said.

A study that has yet to be peer reviewed in previously positive COVID-19 patients who were subsequently vaccinated at least six months later found that participants were able to fight off the two worrisome variants tested: delta, the most infectious, and beta, the deadliest.

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“With a previous infection, their antibodies are able to recognize many variants, but with the addition of the vaccine, they are able to generate a large number to have a more potent effect against the virus,” Crotty said.

As an exercise program that combines weight lifting and cardio, Crotty explained that these people benefit from the combination of the varying amount and quality of the immune response they develop. And that could indicate some promising signs for boosters.

Scientists seek to replicate this strong protection, but without people having to contract COVID-19, as it is universally agreed that infection is not an optimal course of vaccination.

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Instead, they are hoping that booster doses of vaccines might have a similar effect.

But timing is of the essence when it comes to additional doses, regardless of the vaccine given. The researchers say the exact interval when the immune response has matured – but before protection begins to wane – is the ideal target.

“Our immune system is designed to have repeated exposures to the same antigen,” which will “dramatically” improve immune protection, said Dan Barouch, director of the Center for Virology and Vaccine Research at Beth Israel Deaconess Medical Center.

Experts are still gleaning what exactly the benefit of this enhanced immunity is, although it is not new to the coronavirus.

Flu shots, for example, are “boosted” for children who receive them, while adults receive one dose per year.

“It’s because of hybrid immunity. Adults have been exposed to the flu before and have primed their immune response,” Goepfert said.

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“What we have seen is that waiting six months results in a better immune response later,” he added. “It seems our immune system likes to rest and develop antibodies, then mount a stronger response when it sees the same pathogen again later.”

There is not yet enough data to say whether the mixed approach of priming one vaccine and strengthening it with another will provide better or longer lasting protection. But as long as the jury is out, experts hope.

“The mix-and-match approach to administering vaccines has been studied for decades, but unfortunately not for COVID,” Barouch said. “While larger studies are ongoing, it is best to stick with the same vaccine for the booster, if approved.”

Lily Nedda Dastmalchi, DO, MA, is a physician and cardiology fellow at Temple University Hospital, and a collaborator in the ABC News medical unit.

How COVID-19 hybrid immunity could be a game-changer in a pandemic originally appeared on abcnews.go.com