A COVID-19 booster shot may provide protection for years, studies find

A series of studies suggest that a person who gets a COVID-19 booster shot may not need another one for months or even years, according to a story from The New York Times.

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Three doses of a COVID-19 mRNA vaccine are enough to protect most people from serious illness and death, the studies are showing. The protection can last for a long time, researchers said.

“We’re starting to see now diminishing returns on the number of additional doses,” John Wherry, director of the Institute for Immunology at the University of Pennsylvania, told the Times.

Wherry added that while people over 65 or who are immunocompromised may benefit from a fourth vaccine dose, it may be unnecessary for most people.

Another study posted on bioRxiv suggests that the third shot of an mRNA vaccine from Pfizer/BioNTech or Moderna could be effective against variants that have not yet been seen. bioRxiv posts studies that have not been peer-reviewed.

“If people are exposed to another variant like omicron, they now got some extra ammunition to fight it,” said Dr. Julie McElrath, an infectious disease physician and immunologist at Fred Hutchinson Cancer Research Center in Seattle.

The story pointed out that the recent studies match what researchers saw for the SARS coronavirus, which killed nearly 800 people in a 2003 epidemic in Asia. In people exposed to that virus, T cells lasted more than 17 years, studies have shown.

“Memory responses can last for ages,” Wendy Burgers, an immunologist at the University of Cape Town who led one of the studies that was published in the journal Nature, told the Times. “Potentially, the T-cell response is extremely long-lived.”