People who’ve had COVID-19 might only need to get vaccinated once, studies suggest

Six recent studies suggest that people who’ve already come down with COVID-19 might not need to get a second vaccine dose.

The federal government has not changed its recommendation for a second dose, but studies that look at the immune response show that while a first shot gives people who’ve recovered from COVID-19 a huge boost, the second shot makes little difference.

“I think that makes perfect sense,” said Dr. Paul Offit, director of the Vaccine Education Center at Children’s Hospital of Philadelphia.

For someone who had COVID-19, the first shot is like a COVID-19-naive person getting a booster – they even have the side effects of someone getting a second vaccine dose, he said.

“You could argue reasonably that people who can prove they were infected – i.e., have antibodies to the virus – could reasonably just get one dose,” Offit said.

There’s no danger in getting a second shot, for someone who’s had COVID-19, said Florian Krammer, who led one of the recent studies. But it may not provide any benefit for the time and stress it takes to make a reservation, get to and from a vaccination site and watch the needle go in.

And every person who doesn’t need a second shot means a first shot for someone else.

The challenge will be identifying who doesn’t need that second dose, he and others said.

“Implementation might not be that easy,” said Krammer, a professor of microbiology at the Icahn School of Medicine at Mount Sinai in New York City.

Firefighter Anthony MacDougall administers a COVID-19 vaccine to Carmen Limeta at a mobile vaccination site at South Park Recreation Center in Los Angeles.

Anyone who received a formal diagnosis of COVID-19 – not just people who felt lousy for a few days and presumed they’d had it – or people who have antibodies to the virus that causes COVID-19 could presumably skip a second shot.

Last spring, antibody tests were not always reliable, Krammer said, but the ones still on the market now are good, though it’s still not clear if a particular level of antibody is needed to be protected.

Antibody tests, also known as serology tests, detect proteins made by the immune system in response to an infection.

According to Krammer’s study, posted at the beginning of the month but not yet peer reviewed, a previously infected person who gets their first shot has a similar immune response as someone who hasn’t had COVID-19 getting their second. They even have the side effects of a second shot with their first shot.

And that second shot adds little extra protection, the study found.

“Changing the policy to give these individuals only one dose of vaccine would not negatively impact on their antibody titers, spare them from unnecessary pain and free up many urgently needed vaccine doses,” it concluded.

Dr. Francis Collins, director of the National Institutes of Health, wrote about the study in his weekly blog.

“While much more research is needed – and I am definitely not suggesting a change in the current recommendations right now – the results raise the possibility that one dose might be enough for someone who’s been infected with SARS-CoV-2 and already generated antibodies against the virus,” Collins wrote.

“But any serious consideration of this option will require more data. It will also be up to the expert advisors at FDA and Centers for Disease Control and Prevention (CDC) to decide,” he added.

Exactly how much more data or what type of information would be enough to convince regulators isn’t clear.

Another of the new studies, a preprint from the University of Maryland, showed that 41 health care workers who recovered from COVID-19 had more antibodies after their first shot than 69 of their peers who hadn’t caught the virus had after their second.

And a preprint from the Fred Hutchinson Cancer Research Center in Seattle found that blood from people who recovered from COVID-19 was not as good at neutralizing the original virus or the variant that originated from South Africa as blood from people who had recovered and were vaccinated. Three other studies had similar findings.

Each of the six studies publicly released this month looks at the issue in a different way, but “they basically all show the same thing,” Krammer said, “They are confirming each other.”

Contact Karen Weintraub at kweintraub@usatoday.com.

Health and patient safety coverage at USA TODAY is made possible in part by a grant from the Masimo Foundation for Ethics, Innovation and Competition in Healthcare. The Masimo Foundation does not provide editorial input.

Los Angeles health workers administer COVID-19 vaccinations on Feb. 24.

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