Gov't officials remain unconvinced Americans need COVID vaccine booster shot just yet

Americans who are fully vaccinated don’t need another shot, top U.S. health officials said late Monday following a private meeting with top executives at Pfizer, which says it had new data showing a third vaccine dose could boost the body’s antibody response five- to ten-fold.

The statements appear to close the door – at least for now – on the suggestion that people who were among the first to be vaccinated more than six months ago would once again need to line up for a third shot. One factor that could change that calculus is the emergence of new variants of the virus that causes COVID-19.

"At this time, fully vaccinated Americans do not need a booster shot," the Department of Health and Human Sciences said in a statement following the meeting with Pfizer.

Pfizer called its meeting with government health officials "productive" and said it would publish more "definitive data" in a peer-reviewed journal soon.

"Both Pfizer and the U.S. government share a sense of urgency in staying ahead of the virus that causes COVID-19, and we also agree that the scientific data will dictate next steps in the rigorous regulatory process that we always follow," the company said in a statement released Tuesday.

The question of whether and when Americans might need a third shot has been an open question for months, as health experts noted that a person’s detectible antibodies wane over time and as new variants of the virus have emerged. But there are other parts of a person’s immune system, including T-cells, that doctors believe also play a major role in helping prevent hospitalization or death.

The first vaccine shots given in the U.S. were Pfizer doses to health care workers on Dec. 14 – some seven months ago.

But since then, ample real-world evidence has surfaced that vaccinated individuals are strongly protected from the virus and its currently known variants. According to the Centers for Disease Control and Prevention, 99.5 percent of deaths from COVID-19 are among unvaccinated patients.

"Nearly every death, especially among adults, due to COVID-19, is, at this point, entirely preventable," said CDC Director Rochelle Walensky last week.

On July 8, Pfizer announced it had "encouraging data" on the prospects of a third dose. The Pfizer vaccine is typically given in two doses, three weeks apart.

"Initial data from the study demonstrate that a booster dose given after 6 months of the second dose has a consistent tolerability profile while eliciting high neutralization titers, 5-10 times higher than after two primary doses" against variants of the virus, the company stated in an announcement.

"While protection against severe disease remained high across the full 6 months, the observed decline in efficacy against symptomatic disease over time and the continued emergence of variants are key factors driving our belief that a booster dose will likely be necessary to maintain highest levels of protection," Pfizer said in its earlier statement.

After meeting with Pfizer officials, Dr. Anthony Fauci, chief medical adviser to President Joe Biden, told CNN’s Chris Cuomo Monday night that it’s possible the government will recommend boosters eventually, possibly starting with older Americans or people with underlying medical conditions.

But Fauci said he doesn’t think boosters are needed just yet.

"We heard their data. We made it very clear their data is a part of a much larger puzzle, and we will be gathering data as the weeks go by," Fauci said.

Fauci also noted that if a decision on boosters is made, "it will be based on a comprehensive study, not on the announcement of a pharmaceutical company."

Fauci’s statement was a nod to the public confusion about the effectiveness of the vaccine after Pfizer announced it would recommend boosters.

"I don't mean that in a derogatory way because it was a very good meeting, very informative. We exchanged information, and I think it's an important step in the right direction," he added.

In attendance were Drs. Fauci and Walensky, as well as acting FDA Administrator Janet Woodcock; Peter Marks, who has been leading FDA regulatory efforts on the vaccine; Surgeon General Vivek Murthy; Francis Collins, head of the National Institutes of Health; Biden COVID adviser David Kessler; and Rachel Levine, assistance secretary for Health at HHS.

ABC News' Eric Strauss contributed to this report.