White House chief medical adviser Dr. Anthony Fauci said that he and other U.S. health experts want to move away from using the term “fully vaccinated,” and instead want to use a more fluid term for a battery of COVID-19 shots and boosters: “Up to date.”

At the time of this reporting, the Centers for Disease Control and Prevention recommend for U.S. adults and some children a multi-shot series consisting of three shots of an mRNA vaccine such as that developed by Pfizer or Moderna, or a two-dose shot of Johnson & Johnson’s COVID-19 vaccine.

What are the details?

During a Tuesday lecture for the National Institutes of Health, Fauci indicated that there’s no real way of describing what it means to be “fully vaccinated” at this point in time.

He added that “optimal protection” — for now — constitutes every shot available to the appropriate public.

“We’re using the terminology now ‘keeping your vaccinations up to date,’ rather than what ‘fully vaccinated’ means,” Fauci said in remarks according to Bloomberg Law. “Right now, optimal protection is with a third shot of an mRNA or a second shot of a J&J.”

That same day, the CDC called for third shots of Pfizer’s coronavirus vaccine to be administered within five months of completing the initial two-shot series, rather than six months.

In related news …

According to a report from the Associated Press, CDC Director Rochelle Walensky on Wednesday said that the agency is not changing the qualifications for being “fully vaccinated” against COVID-19, but is urging all Americans to be vigilant about remaining up to date with their shots — meaning that there is no federal mandate for booster shots as they pertain to travel or employment at this time.

“Individuals are considered fully vaccinated against COVID-19 if they’ve received their primary series,” Walensky said Wednesday. “That definition is not changing … We are now recommending that individuals stay up to date with additional doses that they are eligible for.”

The report added that on Wednesday, the CDC revised an agency website that was initially titled “When You’ve Been Fully Vaccinated” to “Stay Up to Date with Vaccines.”

A spokesperson for the CDC explained, “[The] CDC will now use the phrase ‘up to date’ when talking about COVID-19 vaccination. CDC recommends that individuals stay ‘up to date’ by receiving any additional doses they are eligible for, according to CDC’s recommendations, to ensure they have optimal protection against COVID-19.”

“Certainly, as Dr. Fauci has demonstrated and even our CDC data have also demonstrated, we are continuing to follow that science and it is literally evolving daily,” Walensky said during a Dec. 15 White House COVID-19 briefing. “And as that science evolves, we will continue to review the data and update our recommendations as necessary.”

Later that same month, Walensky touted the necessity of booster shots.

“Our CDC guidance has been very clear that people should get their boost when they are eligible,” she said at the time. “That is both because of waning immunity and because we need more protection against Omicron.”

Walensky added, “We do know that they do have some protection against severe disease and death but that they do have quite a bit of waning with regard to protection against infection. And since these are guidelines for quarantine, we really wanted to have those measures in place since they have had quite a bit of waning protection against infection.”