Scientific advisors from the Centers for Disease Control and Prevention met Wednesday to decide which Americans should get a booster dose of the Pfizer BioNTech coronavirus vaccine – and when.
The committee’s discussions followed a dramatic exchange at the Food and Drug Administration on Friday when advisors overwhelmingly opposed a proposal to offer Pfizer booster shots to all Americans over the age of 16, but then voted unanimously for the third dose for some high-risk people and those older than 65 years.
On Thursday, CDC advisors will try to be more specific about who qualifies. Depending on the judgment, most Americans or just a select few could be offered booster shots.
The recommendations of the CDC committee are influential but not binding, and state officials sometimes implement their own criteria. In any case, the advice will be late for the Biden administration, which had planned to offer third doses to most fully vaccinated adults in the United States this week.
On Wednesday, the committee addressed unanswered questions in the data available so far.
A third dose will undoubtedly increase antibody levels, the experts said. However, it is unclear how long this surge will last, whether it will lead to a meaningful increase in protection against serious diseases, and whether it can significantly reduce the transmission of the virus. Scientists on the committee also noted the lack of safety data, especially among younger people.
Several counselors said they believed the goal of the boosters should be to prevent serious illness, hospitalizations, and death, rather than infection.
“I just want to encourage us not to clump infections and hospital stays,” said Dr. Sarah Long, a pediatric infectious disease expert at Drexel University College of Medicine in Philadelphia. “I don’t think there is any hope that vaccines like the one we have will prevent infection after the first, maybe a couple of weeks, that you have these extraordinary immediate reactions.”
The advisors also struggled with the practicalities of advocating a booster of the Pfizer vaccine, but not the Moderna or Johnson & Johnson vaccine. Such a recommendation could leave people originally vaccinated with the latter two vaccines feeling unprotected.
“This is a major public health panic that we want to avoid,” said Dr. Long.
Some experts seemed to suggest that they could postpone recommending booster vaccinations altogether if the law did not allow them to recommend the different types of vaccines until they could also receive booster vaccinations.
Moderna asked the FDA this month to approve a half dose of its vaccine as a booster shot. Federal regulators are reviewing Moderna’s data to see if they support the approval.
Earlier in the day, counselors heard detailed evidence about the different types of immunity produced by the vaccines. Natalie Thornburg, a CDC scientist, presented results from a number of studies that suggested that falling antibody levels might have little impact on protection against serious illness. Some subsets of antibodies are needed to prevent infection, but immune cells that prevent the disease from progressing are stable, she said.
“Antibodies decrease over time as expected in all age groups, but cellular memory is preserved,” she said. However, immunity is known to decrease in adults over 80, but this suggests that boosters may be needed for this age group. And a CDC study showed a decrease in vaccines’ ability to prevent serious illness in adults over 65.
Boosters can reduce the incidence of nursing home residents, who are among the most vulnerable, according to the results of a model study described at the meeting. But even with highly potent boosters, cases will persist in nursing homes if transmission is high in the community, said Rachel Slayton, a CDC researcher who introduced the model.
Understand US vaccination and mask requirements
- Vaccination rules. On August 23, the Food and Drug Administration fully approved Pfizer-BioNTech’s coronavirus vaccine for people aged 16 and over, paving the way for increased mandates in both the public and private sectors. Private companies are increasingly demanding vaccines for employees. Such mandates are legally permissible and have been confirmed in legal challenges.
- Mask rules. The Centers for Disease Control and Prevention in July recommended that all Americans, regardless of vaccination status, wear masks in public places indoors in areas with outbreaks, a reversal of the guidelines offered in May. See where the CDC guidelines would apply and where states have implemented their own mask guidelines. The battle over masks is controversial in some states, with some local leaders defying state bans.
- College and Universities. More than 400 colleges and universities require a vaccination against Covid-19. Almost all of them are in states that voted for President Biden.
- schools. Both California and New York City have introduced vaccine mandates for educational staff. A survey published in August found that many American parents of school-age children are against mandatory vaccines for students, but are more likely to support masking requirements for students, teachers and staff who are not vaccinated.
- Hospitals and medical centers. Many hospitals and large health systems require their employees to have a Covid-19 vaccine, due to rising case numbers due to the Delta variant and persistently low vaccination rates in their communities, even within their workforce.
- New York City. Proof of vaccination is required by workers and customers for indoor dining, gyms, performances, and other indoor situations, although enforcement doesn’t begin until September 13. Teachers and other educational workers in the city’s vast school system are required to have at least one vaccine dose by September 27, without the option of weekly testing. City hospital staff must also be vaccinated or have weekly tests. Similar rules apply to employees in New York State.
- At the federal level. The Pentagon announced that it would make coronavirus vaccinations compulsory for the country’s 1.3 million active soldiers “by mid-September at the latest. President Biden announced that all civil federal employees would need to be vaccinated against the coronavirus or undergo regular tests, social distancing, mask requirements and travel restrictions.
Vaccination staff in nursing homes and other prevention strategies to limit transmission will continue to be important, she said.
Some global health experts have criticized the Biden government for pushing booster injections when a large part of the world’s population has not yet received a first dose. But on Wednesday, White House press secretary Jen Psaki reiterated the government’s argument that it was possible to offer boosters to Americans while vaccinating the rest of the world.
On Wednesday morning, President Biden said the United States would buy and donate 500 million doses of the Pfizer BioNTech vaccine, in addition to the 500 million the government bought in July.
“We are now donating three shots around the world for every shot we give an American in the arm, and we continue to believe that we can do both and that it is a wrong decision,” said Ms. Psaki. “We still believe that the rest of the world must have been open and do more.”
At the FDA advisors’ meeting on Friday, senior scientists from Pfizer and the Israeli Ministry of Health presented data that they believed indicated declining immunity in people who had received the Pfizer vaccine months earlier. Boosting the immune system with a third shot made a difference in Israel and could stem the tide of infections in the United States.
The FDA advisors also evaluated data from the CDC on the trajectory of the virus in the United States, as well as summaries of several studies on the effectiveness of the vaccines.
However, after reviewing the evidence, the committee’s scientists concluded that while protection against infection may decline, especially in older adults, the original two-shot therapy still provides excellent protection against serious illness and hospitalization for most people .
“It is unclear that everyone needs topping except for a subset of the population who would clearly be at high risk for serious illness,” said Dr. Michael G. Kurilla, a committee member and officer for the National Institutes of Health.
Daniel E. Slotnik contributed the reporting.