Boosters for all three manufacturers' COVID-19 vaccines may soon be available.

But, UPMC doctors said Friday, booster shots are one, minor part of the solution.

“The most important job right now in immunization is to get those who haven't yet decided to get fully vaccinated ... to the point where they are choosing the vaccine and getting the vaccine,” Dr. Donald Yealy said in a media briefing. “That is, far and away, the most important job right now, as opposed to booster doses for most of the population.”

Yealy, emergency medicine chairman at UPMC, said the vaccines created by all three manufactures — the mRNA shots made by Pfizer/BioNTech and Moderna, as well as Johnson & Johnson's adenovirus vaccine — continue to be effective at both preventing infection and preventing serious symptoms and hospitalization.

According to Dr. Graham Snyder, director of infection prevention and hospital epidemiology, the boosters are there to “remind our immune system to be fully prepared,” but noted the three vaccines continue to “do really, really well” at keeping vaccinated individuals well.

“It's not that you need a booster because, all of a sudden, you're completely unprotected again,” Yealy said. “The people who are unprotected are the people who haven't chosen to get the vaccine yet and the very small portion of the population” whose immune response to the vaccine was inadequate.

Yealy also said the booster shots are most important in that latter group of people, which includes immunocompromised individuals.

“If you've already had a vaccine series and you're not immunocompromised ... it's important to consider boosting, but you can walk to get that booster; you don't have to run to it,” he said. “You're well-protected already.”

Reaching more people

Yealy said there are myriad reasons why some people aren't yet vaccinated. The solution to that, he said, is to build trust between unvaccinated people and the medical professionals.

“We want them to become more comfortable and get the vaccine,” he said. “That's going to require lots of small conversations, trust-building between providers and the patients. That is the most important step right now.”

It may feel like the mRNA technology used in two-thirds of the available immunizations is new, Yealy said, but it's not. He said physicians and scientists have been working with mRNA for years — as well as with treatments like monoclonal antibodies — “they just are (new) to the public.”

Snyder agreed, and said the vaccines, including both the mRNA and viral vector shots, have been studied ad nauseam.

“They have many more observations than other vaccines that are this young in their development, and the mRNA technology is not really new at all,” he said. “We have an incredible abundance of data.”

That said, both Yealy and Snyder added they understand why some people are hesitant. But they want to ensure the vaccine-hesitant individuals are aware of the data surrounding the vaccines' safety.

“We have some of the most intense scrutiny, and they've been used in hundreds of millions of patients now,” Yealy said. “We know more about these vaccines than almost any other vaccine, including ones that have been around for a long period of time.”

The quick deployment of the three shots doesn't mean there's a likelihood of adverse reactions to them years later, either.

“They almost never, in the history of any vaccine, show up after a very, very long delay. We're now almost a year into this and I do not think there are going to be uncertain or heretofore unconsidered long-term effects,” Yealy said. “Almost without fail the side effects of getting the infection, COVID-19, are incredibly worse: They're more frequent, more severe and harder to shake than anything you could imagine or observe from the vaccine.”

Boosting

Much of the data on the continued effectiveness of the vaccinations, Yealy said, stems from the antibody levels in immunized people.

“That's just one part of the immune response,” he said. “It's actually a response that your body can remember and amplify, whether it gets another dose of the vaccine or if it encounters the virus.”

Antibodies are the part of the immune system that actively attack invading germs. According to the CDC, they are produced by B-cells, which can be recalled by memory T-cells when the latter encounter a familiar germ.

Yealy said a booster would, for lack of a better term, exercise the immune system.

“The booster is not there to fundamentally change the pandemic” the way the original vaccines did, he added.