The Biden administration is facing controversy over its acceptance of Pfizer-BioNTech's application to authorize the COVID-19 vaccine for children under 5 without showing completed clinical trial data, and officials are now scrambling to convince the public that the accelerated process is not sacrificing science.

Pfizer-BioNTech submitted part of its application to the Food and Drug Administration on Tuesday to authorize a 3-microgram-dose COVID-19 vaccine for children under five. The company had initially tested a two-dose regimen in children but announced in December that adding a third dose would be necessary to prompt an immune response. But the clinical trial data to support the authorization of a three-dose regimen is missing results from administering the third dose, causing concern that the agency is sacrificing science for expediency.


While Pfizer does not expect to have clinical trial data for third doses until April, the FDA will not wait until the data is complete to review safety and efficacy data for the first two shots. Now, the agency is on the defensive.

“We want to set the record straight on the recent developments on the Pfizer-BioNTech COVID-19 Vaccine for children 6 months through 4 years of age,” Food and Drug Administration spokesman Michael Felberbaum wrote on Wednesday. “Nothing has changed about our process for evaluating COVID-19 vaccines and we are not changing our rigorous scientific standards.”

In reviewing the clinical trial data for vaccines for children, FDA researchers measure the body's physiological response to the vaccine rather than its ability to stave off infection. When a foreign antigen like the coronavirus enters the body, the immune system is trained to recognize it and unleash a strong defense to destroy it. Sometimes, an immune response will manifest itself in physical symptoms. This is why one of the most common adverse effects of vaccination is fever — a higher temperature makes the body less hospitable for the virus, and the rise in temperature prompts the body to generate more immune cells. Adverse effects such as fever, fatigue, and body aches are indications that the vaccine is working to build up bodily protection against the virus.

Still, the shots were effective at preventing infection, a metric that scientists did not set out to study but took note of when some subjects of the trial got infected, according to the New York Times. Children age 2 to 4 who were given two shots were infected at a rate 57% lower than the children in the placebo group.

While the shots did not mount the desired immune response in children 2 to 5, the 3-microgram dose, a 10th the size that people 12 and older would get, was found to be safe and well tolerated.

The Biden administration urged Pfizer-BioNTech to submit the data it had on two doses in the hope of getting a jump on pediatric vaccinations while additional data from the third dose roll in. The rapid spread of the omicron variant, which has also proven adept at infecting even fully vaccinated people, necessitated the accelerated review process, the Biden administration argued.

“There is a big change that's happened, which is we experienced the omicron surge,” Surgeon General Vivek Murthy said on Wednesday. “With many children in particular, as well as adults being infected and ending up in the hospital during the omicron surge, it turns out that has actually facilitated the collection of important clinical data, additional clinical data, that we did not have in December.”

The FDA’s move to push the company to submit data on a rolling basis was an unusual one. It is customary for the agency to require drugmakers to submit all available clinical trial data before considering authorization. Pfizer has kept clinical trial data under wraps from the public, instead offering a truncated explanation of trial results in a press release.

Some doctors have questioned the agency's reasoning for accepting data on a rolling basis, noting that scientists are placing too much weight on that third shot to make the vaccine regimen effective.

“It doesn’t make sense we would approve a two-dose vaccine on the assumption the third dose would make up for deficiencies of the two doses,” Dr. Paul Offit, a member of the FDA’s vaccine advisory group and director of the Vaccine Education Center at the Children’s Hospital of Philadelphia told the New York Times.

To date, children 5 and up can get the Pfizer shots. They were authorized last fall for use in children 5 through 11 after clinical trials found that the lower-dose version of the vaccine was 90.7% effective in preventing symptomatic COVID-19 among that age group. The authorization process for Pfizer shots in that age group was speedy — about four weeks elapsed between submitting the application to the FDA and getting authorization for the shots.

Still, some doctors worry that the FDA has risked losing the trust of parents who may have existing concerns about the safety and long-term effects of the vaccines in children. Only 31% of parents said they would get their children under 5 vaccinated as soon as the vaccine is authorized, while another 29% said they will “wait and see” before getting their child under 5 vaccinated, down from 40% in July. For instance, Dr. Jeremy Faust, an emergency physician at Brigham and Women's Hospital in Boston, said he will not vaccinate his 3-year-old daughter until more complete data about the efficacy of third doses comes out.

“This strategy could come at a cost if other parents lose faith in the scientific process,” Faust said. “I’m worried that if we rush now, there will be fewer young children vaccinated by next fall than if we wait a few more weeks. I’m less interested in vaccination rates in the next 6 weeks and more interested in vaccination rates in the next 6-12 months.”

The United States is unique in its move to authorize shots in the youngest portion of the population. The European Union and other countries such as Canada and the United Kingdom have authorized shots for children as young as 5, but not younger. Children are also at considerably lower risk of becoming severely ill due to COVID-19 than older adults and people with underlying health conditions such as heart disease and diabetes.


The FDA’s panel of vaccine experts will meet on Feb. 15 to consider Pfizer’s application for expanded authorization. Clinical data supporting the application for expanded authorization will be made publicly available in time for the meeting.