With booster shots now authorized by FDA for every adult recipient of the Pfizer-BioNTech and Moderna Covid-19 vaccines, a debate is rising over the definition of "fully vaccinated.” Some officials are already looking to change the criteria to include booster shots.

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Some leaders express interest in changing the definition of 'fully vaccinated'

In recent days, two U.S. governors have said they believe "fully vaccinated" means having three shots of an mRNA vaccine rather than two.

"We're 11 months into the vaccination program," Connecticut Gov. Ned Lamont (D), said. "In my view, if you were vaccinated more than six months ago, you're not fully vaccinated."

Similarly, New Mexico Gov. Michelle Lujan Grisham (D) on Wednesday urged all adults in her state to get their booster shots when eligible.

"We know vaccinations are the most effective tool to both blunting the spread of the virus and to protecting [ourselves] and our families," she said. "So we are analyzing what we can do to create those incentives—and potentially mandates—for making sure that people are fully vaccinated, which means three vaccines."

New Mexico Health and Human Services Secretary David Scrase said discussions are being held about changing the definition of "fully vaccinated" in the state, and he anticipates a public health order will be released in the coming weeks.

In the United Kingdom, Prime Minister Boris Johnson on Monday also said he believes the definition of "fully vaccinated" is slated to change in the future, though he didn't provide a specific time frame on the change.

"It's very clear that getting three jabs, getting your booster, will become an important fact and it will make life easier for you in all sorts of ways," Johnson said.

"We will have to adjust our concept of what constitutes a full vaccination to take account of that, and I think that is increasingly obvious," he added.

Where public health officials stand

Currently, there are no plans to change the definition of "fully vaccinated" on a federal level in the United States. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, said earlier this week that a definition change "hasn't been on the table yet," but didn't rule out the possibility.

According to ABC News, Fauci said a third dose of an mRNA shot, "should be part of the actual standard regimen, where a booster isn't a luxury; a booster isn't an add on; and a booster is part of what the original regimen should be—so that when we look back on this, we're going to see that boosters are essential for an optimal vaccine regimen."

In addition, last month, CDC Director Rochelle Walensky said a change in definition hasn't occurred yet since only certain groups are currently eligible for booster doses, but added that the definition may change in the future as more information becomes available.

"We have not yet changed the definition of 'fully vaccinated.' We will continue to look at this," she said. However, she later clarified that, at present, the "definition of 'fully vaccinated' is one dose of the Johnson & Johnson vaccine and two doses of the either Pfizer vaccine or the Moderna vaccine, and we're not examining changing that definition anytime at this point," The Hill reports.

Walid Gellad, a professor of medicine at the University of Pittsburgh, pushed back on changing the definition of "fully vaccinated," saying it "would have major implications across many aspects of the pandemic, in some cases making it more difficult to control."

"We haven't thought through all the implications to start saying this casually," he added. "It's premature." (NBC Connecticut, 11/18; Bryan, Associated Press, 11/18; Reuters, 11/15; Owens, Axios, 11/19; Pezenik, ABC News, 11/16; Barnes, The Hill, 11/3)