Why changing the definition of ‘fully vaccinated’ could be difficult

The US Centers for Disease Control and Prevention might consider redefining what it means to be “fully vaccinated” against Covid-19 to include a third dose of vaccine — but the question is when the definition could change.

Such a change is “on the table and open for discussion,” Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, said Friday.

“That’s certainly on the table. Right now, it is a bit of semantics,” Fauci told CNBC’s Andrew Ross Sorkin on “Squawk Box.” Fauci was referring to the definition of “fully vaccinated” for the purpose of regulations or businesses that may require vaccination.

“But there’s no doubt that optimum vaccination is with a booster,” he added.

“I’m not sure exactly when that will happen,” he said. “But I think people should not lose sight of the message that there’s no doubt that if you want to be optimally protected, you should get your booster.”

What it means to be “fully vaccinated” against Covid-19 is starting to play a big role in most Americans’ lives — and being fully vaccinated not only offers some protection against the virus, it comes with certain liberties.

For some adults, whether they fall under the definition of “fully vaccinated” dictates whether they can go into work. For some families, being fully vaccinated would allow them to travel out of the country. For some children, being fully vaccinated is required to attend school in person.

But those requirements, based on the current definition, have already met with some pushback.

In October, members of the New York City Fire Department gathered to protest Covid-19 vaccine requirements for city workers. In June, a group of Houston Methodist Hospital workers protested the health care system’s requirement that staffers be vaccinated against Covid-19.

Changing the definition could create some logistical challenges.

‘Changing that definition is a difficult endeavor’

Currently, the CDC’s interim clinical considerations define “fully vaccinated” as having completed two doses of either the Pfizer/BioNTech or Moderna coronavirus vaccines, or a single dose of the Johnson & Johnson vaccine.

“Administration of an additional primary dose or a booster dose is not required to be considered fully vaccinated for public health purposes at this time,” according to the CDC’s website, last updated last week.

Meanwhile, private businesses, states and other local jurisdictions could establish their own definitions of “fully vaccinated” to include booster doses well before the federal government, Dr. Scott Gottlieb, a former commissioner of the US Food and Drug Administration, told CNBC’s Rebecca Quick on “Squawk Box” on Friday.

“I think states are going to have a hard time doing it, so long as the booster is under an emergency use authorization and it’s unclear when FDA is going to give full approval to the booster — probably some time soon,” Gottlieb said.

But the federal government has “tied a lot of decisions to the definition of what it means to be fully vaccinated, and changing that definition is a difficult endeavor, at least from their perception,” Gottlieb said. “So, I think that they’re going to be reluctant to do that. I wouldn’t expect them to do that, certainly until the booster is fully licensed but maybe until next fall.”

In the future, the definition of “fully vaccinated” — moving from two doses to three of mRNA vaccine or moving from one to two doses of J&J vaccine — could change as vaccine makers seek approval or amended emergency use authorizations (EUAs) of their vaccines under the FDA, according to Nancy Allen LaPointe, an adjunct associate professor in medicine and faculty fellow at the Duke-Margolis Center for Health Policy at Duke University.

The Pfizer/BioNTech coronavirus vaccine is the only one in the United States that is FDA approved, “and the labeling, based upon the submitted data, is for the primary 2-dose series,” LaPointe noted in an email to CNN on Thursday.

The Moderna and Johnson & Johnson coronavirus vaccines are still under EUA.

“With regards to all vaccine products and uses under EUA, the EUAs already provide the authorization for booster doses for adults (and Pfizer booster for those 16 and 17 years old). It is possible that the EUAs could be further amended as more data is received to strengthen the language around booster doses,” LaPointe wrote, adding that the CDC could then expand or revise its guidance to further recommend boosters more strongly.

“The CDC could revise recommendations; however, they must stay within any constraints” of an EUA or biologics license application (BLA).

“It may be more accurate to begin to view this in terms of being ‘up-to-date’ with the current recommendations as they will likely continue to evolve and people enter into the vaccination process at different points in time,” she added. “In addition, we don’t know yet whether additional booster doses will be needed in the future — that is will prevention of serious COVID outbreaks and disease require periodic boosters for some or all.”

CDC stands by current ‘fully vaccinated’ definition

Some physicians and scientists are calling on the Biden administration and the CDC to declare that people are no longer fully vaccinated if it has been more than six months since completing their second dose.

“In fact, I think the administration should move the window to four months and allow people who are four months out from the second shot to be boosted,” Dr. Jonathan Reiner, a CNN medical analyst and a professor of medicine and surgery at George Washington University, told CNN’s Pamela Brown on Saturday.

During a White House briefing Wednesday, CDC Director Dr. Rochelle Walensky declined to provide specific details on whether or when the agency would change the definition of “fully vaccinated” from its current definition, saying data was being evaluated and recommendations would be updated “as necessary.”

“The definition right now is two doses of an mRNA vaccine or a single dose of the J&J vaccine,” Walensky said in response to a question from CNN’s Jeremy Diamond.

“We are continuing to follow that science, and it is literally evolving daily,” Walensky added. “And as that science evolves, we will continue to review the data and update our recommendations as necessary.”

Coronavirus vaccine booster shots can help improve protection against the Omicron variant, and there is no need for a variant-specific booster dose at this time, Fauci said in the same briefing.

Fauci added that the effectiveness of the Pfizer/BioNTech coronavirus vaccine against symptomatic Omicron infection is significantly lower than against the Delta variant, but a booster dose increases the effectiveness against Omicron to 75%.

“I’ve always said this is a three-dose vaccine,” Dr. Peter Hotez, a professor and dean of tropical medicine at the Baylor College of Medicine, told CNN’s Alisyn Camerota and Victor Blackwell on Wednesday.

“The reason is, when you get that third dose, you get a 30- to 40-fold rise in virus-neutralizing antibodies, and therefore there’s more spillover protection against new variants, including Omicron,” Hotez said. “The third dose gives you 70% to 75% protection against symptomatic illness.”

It could simply be “a matter of time” before the “fully vaccinated” definition changes, Michael Osterholm, director of the Center for Infectious Disease Research and Policy at the University of Minnesota, told CNN’s John King on Thursday.

“We now have a much better understanding of why the booster is so important,” Osterholm said. “It can have a major impact potentially on whether someone has a serious illness with either Delta or Omicron or a more mild illness — so I’m convinced that this is just a matter of time before this change occurs.”

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