An independent advisory committee to the Centers for Disease Control and Prevention voted overwhelmingly on Saturday to recommend use of the Covid-19 vaccine made by Pfizer and BioNTech.
But the meeting also revealed an apparent divide in thinking on whether the vaccine should be given to people with a history of severe allergic reactions to other medicines, a determination that could prevent hundreds of thousands of people from receiving it.
During a presentation before the committee, a CDC official provided advisory language suggesting that any individual with a history of a severe allergic reaction to an injectable medication or vaccine should not receive the Pfizer/BioNTech product, which was granted emergency authorization by the Food and Drug Administration late Friday. Two health care workers in Britain experienced a severe reaction earlier this week after vaccinations started outside of clinical trials.
But the FDA, in issuing its emergency use authorization, only warned against using the vaccine in people who had previously had severe reactions to ingredients in this particular vaccine, not any vaccine or injectable drug.
Severe allergic reactions to vaccines are extremely rare and were also rare during the Pfizer and BioNTech trial, which excluded people with a history of the severe allergic reaction known as anaphylaxis. The FDA has released data indicating .63% of participants who received the vaccine experienced serious adverse reactions, compared to .51% of people who received a placebo.
In a press conference Saturday, Peter Marks, director of the FDA’s Center for Biologics Evaluation and Research, emphasized that the FDA will continue to monitor the prevalence of severe allergic reactions associated with the Pfizer/BioNTech vaccine, and that it may need to revise its warnings moving forward.
He added, however, that the agency feels comfortable barring only those with a history of severe reactions to an ingredient in the vaccine, as opposed to barring all Americans with a history of any severe allergic reaction.
“It turns out about 1.6% of the population has had a severe allergic reaction of some sort or another to a food or some environmental aspect and we would really not like to have that many people not be able to receive the vaccine, so we looked very closely at the databases, and we feel comfortable that we’re telling people that unless they’ve had a severe allergic reaction to the vaccine, or one of its components, they can receive it,” Marks said. “We may have to modify things as we move forward, but for right now we’re comfortable with this.”
CDC officials expect to finalize their guidance on Sunday on who should receive the vaccine and how health care providers should discuss the risks with different groups of patients. Conflicting advice for those with a history of allergic reactions could create confusion as the first doses are delivered on Monday.
The discussion on severe reactions occurred during a marathon meeting of the CDC Advisory Committee on Immunization Practices, known as ACIP. The committee voted 11-0 to recommend vaccination for people age 16 and older; three members recused themselves because of participation in the vaccine trials or other conflicts.
On the question of allergic reactions, some committee members raised questions about how the language would be understood by the public, as providers and ordinary citizens may have a different understanding of what constitutes a severe allergic reaction. Others raised questions about whether the language was overly broad and would be needlessly applied to people with food and environmental allergies.
“I recognize the rationale for including this, but I am a little nervous about the abundance of caution,” said committee member Beth Bell, a physician and professor of global health at the University of Washington. “I’m wondering if there could be further clarification…so there’s a clear distinction between what we’re concerned about and this much broader group of allergies that involves an awful lot of people who don’t need to be included in this.”
A CDC official replied that Bell’s suggested distinction would be added to the agency’s advisory language.
The discussion, coming shortly before the first doses are delivered, underscored the breakneck pace at which federal officials are working to finalize guidelines on who should receive the vaccine amid unclear clinical evidence.
The two British health care workers who had reactions had previously experienced anaphylaxis because of food allergies, but it is not known whether an ingredient in the vaccine caused the reactions. An investigation is ongoing.
In considering other groups, the advisory committee members broadly agreed there is no evidence to suggest that women who are breastfeeding should not receive the vaccine; they also agreed that women who are pregnant may receive the vaccine after discussing the risks and benefits with their doctors.
There was some debate on the evidence of safety for 16- and 17-year-olds. Henry Bernstein, a pediatrician and professor at the Zucker School of Medicine at Hofstra University, suggested that 16 and 17 year olds should be designated as a “special population” to recognize that data is limited in that age group.
“A successful pediatric vaccination program depends on creating and sustaining parental confidence in both the safety and effectiveness of this vaccine,” he said.
Other panel members disagreed, noting the trial produced no evidence of safety concerns in that age group.
Even with uncertain evidence in some patient groups, committee members agreed that the benefits of the vaccine outweigh the risks and that it should be distributed broadly. Some members said they were concerned that distribution by state and local officials is being underfunded and urged that federal officials allocate more resources to that effort.
“I want to re-emphasize the need for substantially increased government funding to actually implement this recommendation,” said committee member Peter Szilagyi, a pediatrician at UCLA. “We’re going to have tough and sad times ahead because of the surge and the limited vaccine supply, but I am hopeful that this is the beginning of the end of the coronavirus pandemic.”