Centers for Disease Control and Prevention (CDC) Director Rochelle Walensky, MD, MPH, is defending her decision to overrule her own vaccine advisory committee after they voted against giving COVID-19 booster shots to healthcare workers, teachers, and other essential workers at occupational risk of infections.

The surprising 9-6 “no” vote by the CDC Advisory Committee on Immunization Practices (ACIP) rejected a generally worded “occupational” risk recommendation on boosters at a Sept. 23, 2021. Walensky overruled the panel on the occupational booster question in an email statement sent at 12:27 a.m. September 24. The rapidity and decisiveness of that revocation has rarely been seen between the CDC and its advisory committees.

“It’s not something you see very often,” said Ann Marie Pettis, RN, BSN, CIC, president of the Association for Professionals in Infection Control and Epidemiology. “The turnaround was so quick it made your head snap, but it made sense to me. The booster is optional. It is not being required. Healthcare workers have been putting their lives on the line and they at least deserve that option.”

Walensky explained her decision at a White House pandemic press briefing after the booster approval.1

“As CDC director, it’s my job to recognize where our actions can have the greatest impact,” she said. “In a pandemic, we must often take steps with the intention to do the greatest good even in an uncertain environment, and that is what I’m doing with these recommendations. I want to be clear: We will not boost our way out of this pandemic. Infections among the unvaccinated continue to fuel this pandemic.”

Concerns about waning vaccine and the ongoing nursing shortage also support the booster decision, Pettis says.

“We have to preserve the healthcare workforce, both for their safety and patient,” she says. “To me, it’s a risk calculus that had to be made. I understand ACIP was trying to be very measured and it’s true that there are data missing. We are in uncharted waters. I understand their hesitancy and [Walensky] had to make a tough decision, but I think it was the right one.”

In a contentious debate at the end of a long two-day meeting, one of the reasons cited against the recommendation was that healthcare workers have a greater risk of acquiring COVID-19 in the community than at work.

The “occupational” rationale is not actually supported by evidence, since healthcare workers are protecting themselves with personal protective equipment and other measures at work, noted ACIP member Beth Bell, MD, MPH, of the University of Washington in Seattle.

“I don’t believe [the recommendation] is scientifically correct,” she said at the meeting. “Perhaps a case could be made for healthcare workers to reduce the incidence of infections they get because of exposure in the community, and therefore reduce absenteeism among vaccinated healthcare workers.”

That may strictly be true given the protective measures taken in hospitals, but there always is the risk of a breach in protocol, an unanticipated direct exposure, or something potentially more widespread, such as not using a negative pressure room to perform an aerosol-generating procedure on a COVID-19 patient.

At the ACIP meeting, concern was expressed about loose wording in the “occupational” recommendation that could negate the purpose of designating groups and let everybody be boosted pell-mell.

“We might as well as just say, ‘Give it to everybody 18 and over,” said ACIP member Pablo Sanchez, MD, of Ohio State. “We have a really effective vaccine, and this is like saying, it is not working — and it is working. Certainly, some high-risk individuals do have waning immunity with time, but I am concerned about this.”

At this point, the narrative was going off track, particularly since the Food and Drug Administration (FDA) had approved a similar recommendation only a day before the ACIP meeting.

ACIP chair Grace Lee, MD, MPH, of Stanford, was cool under pressure, reminding the committee that the benefit-risk calculation for the recommendation is “individualized,” meaning those at risk of occupational exposures who are fully vaccinated can choose to get the booster — or not. On the other hand, the benefit in passing the recommendation would be providing greater “access” to the booster, which in turn opens a wider path to equity, she emphasized.

Although CDC officials reminded ACIP that the recommendation will be accompanied by education and close follow-up for myocarditis — a rare side effect primarily seen in young men — one ACIP member said the effect of the booster actually could increase risk for this population by prompting a strong antibody response.

“If an 18-year-old is anxious about myocarditis, we are not providing anything in the benefit department, but we are providing risk,” said ACIP member Sarah Long, MD, of Drexel University.

Other ACIP members argued it was necessary to maintain the healthcare workforce and preserve morale amid massive burnout and a national nursing shortage. Still, in general, many ACIP members seemed unenthusiastic about the boosters, citing competing pandemic priorities — including immunizing children — and frustration at focusing on those already vaccinated when so many are not. The tipping point probably came when an ACIP member called the recommendation a “solution looking for a problem.”

The ACIP meeting ended shortly after the occupational booster recommendation was rejected. In addition to the other reasons cited, Walensky’s quick move to overrule the vote also suggests the agency foresaw a potential public relations debacle. It is not hard to imagine news reports going out saying that healthcare workers — the heroes of the pandemic — were being denied the full measure of vaccine protection.

CDC, FDA Booster Recommendations

Here is the CDC occupational recommendation as reissued and approved by Walensky:

“People aged 18 to 64 years who are at increased risk for COVID-19 exposure and transmission because of occupational or institutional setting may receive a booster shot of Pfizer-BioNTech’s COVID-19 vaccine at least six months after their Pfizer-BioNTech primary series, based on their individual benefits and risks.”

A key difference is that the word “recommended” was deleted from the original ACIP proposal, which now instead emphasizes that those in the occupational category “may” get the booster.

The other booster recommendations approved by ACIP and the CDC are:

  • people 65 years of age and older and residents in long-term care settings should receive a booster shot of Pfizer-BioNTech’s COVID-19 vaccine at least six months after their Pfizer-BioNTech primary series;? 
  • people aged 50 to 64 years with underlying medical conditions should receive a booster shot of Pfizer-BioNTech’s COVID-19 vaccine at least six months after their Pfizer-BioNTech primary series;2
  • people aged 18 to 49 years with underlying medical conditions may receive a booster shot of Pfizer-BioNTech’s COVID-19 vaccine at least six months after their Pfizer-BioNTech primary series, based on their individual benefits and risks.2

The FDA recommendations, finalized after a Sept. 17, 2021, meeting of its Vaccines and Related Biological Products Advisory Committee, were similar to the CDC’s. One exception is that the ACIP panel lowered the age range for those at high risk to 50 years of age, in a nod to health disparities among minorities and ethnic populations.

Walensky’s statement said the agencies are in alignment, but there is much more to be done because the FDA only issued an Emergency Use Authorization (EUA) for a Pfizer booster. The FDA recommended boosters for individuals are:3

  • 65 years of age and older; 
  • 18 through 64 years of age at high risk of severe COVID-19; 
  • 18 through 64 years of age whose frequent institutional or occupational exposure to SARS-CoV-2 puts them at high risk of serious complications of COVID-19, including severe COVID-19.

In an initial vote, the FDA decided vaccine efficacy was still sufficient in immune-competent people in the general population, dashing President Biden’s hopes of a large national rollout of booster shots. A lack of overall data and the concern for myocarditis side effects in young people were among the reasons cited before the 16-2 vote against broad immunization with booster doses.

In comments to fellow FDA committee members, Paul Offit, MD, a vaccine expert at the Children’s Hospital of Philadelphia, summed up the situation.

“The stated goal of this vaccine for people like Rochelle Walensky and others has been to protect against serious illness,” he said. “The data presented shows that the vaccine still does exactly that. It is also clear, however, that the third dose of mRNA vaccine increases the titer of virus-specific neutralizing antibodies and will likely decrease the incidence of asymptomatic or symptomatic infection, which is associated with contagiousness. So, then the question becomes what will be the impact of that on the arc of the pandemic? It may not be all that much. Certainly, we all agree that if we really want to impact this pandemic, we need to vaccinate the unvaccinated.”

The FDA said the most common booster side effects among clinical trial participants were pain, redness, and swelling at the injection site. Also reported were fatigue, headache, muscle or joint pain, and chills. “Of note, swollen lymph nodes in the underarm were observed more frequently following the booster dose than after the primary two-dose series,” the FDA reported.

In terms of efficacy, the FDA said it looked at real-world data from the United States and international sources, including the United Kingdom and Israel. “The immune responses of approximately 200 participants 18 through 55 years of age who received a single booster dose approximately six months after their second dose … demonstrated a booster response,” the FDA said.

The degree of that response of was not detailed by the FDA, but researchers in Israel found that the booster dose reduced COVID-19 infection more than 10-fold compared to those who were vaccinated at least five months previously but were not boosted.

“Our findings can be understood through the following example,” the authors explained.3 “Suppose, first, that the combined effect of waning immunity and the increased prevalence of the delta variant decreases the efficacy of a vaccine that had been administered six months earlier to approximately 50% relative to the susceptibility in an unvaccinated person, as recent reports have suggested. Then suppose that, as suggested by our results, the booster dose reduces the rate of infection for such vaccine recipients by a factor of 10. This would mean that the susceptibility of a person who receives a booster dose would decrease to approximately 5% (i.e., 50% divided by 10) relative to that in an unvaccinated person and would bring the vaccine efficacy among booster recipients to approximately 95%, a value similar to the original vaccine efficacy reported against the alpha variant.”  


  1. The White House. Press briefing by White House COVID-19 Response Team and Public Health Officials. Published Sept. 24, 2021.
  2. Centers for Disease Control and Prevention. COVID-19. People with certain medical conditions. Updated Aug. 20, 2021.
  3. U.S. Food and Drug Administration. FDA authorizes booster dose of Pfizer-BioNTech COVID-19 vaccine for certain populations. Published Sept. 22, 2021.
  4. Bar-On YM, Goldberg Y, Mandel M, et al. Protection of BNT162b2 vaccine booster against Covid-19 in Israel. N Engl J Med 2021;385:1393-1400.