FDA, Pfizer abandon 2-shot COVID vaccine in kids under 5, citing new data

The Food and Drug Administration, Pfizer, and BioNTech announced on Friday that they are abandoning plans to pursue the authorization of a two-dose regimen of COVID-19 vaccines for children ages 6 months to 4 years. Instead, they will again put the possibility of an authorization on hold as they await data on the efficacy of a third dose for the youngest children. That data is now expected in early April. In a press release this afternoon, Pfizer and its partner BioNTech reported that COVID-19 cases among children enrolled in the initial two-dose trial "continue to accumulate according to the study protocol, and more data are being generated because rates of infection and illness remain high in children of this age, especially due to the recent omicron surge." "Given that the study is advancing at a rapid pace, the companies will wait for the three-dose data as Pfizer and BioNTech continue to believe it may provide a higher level of protection in this age group," the press release continued. In a statement released by the FDA, Acting Commissioner Janet Woodcock and top vaccine regulator Peter Marks wrote that the agency had received new trial data from Pfizer and BioNTech. "Based on the agency’s preliminary assessment, and to allow more time to evaluate additional data, we believe additional information regarding the ongoing evaluation of a third dose should be considered as part of our decision-making for potential authorization," the officials wrote. In December, Pfizer and BioNTech announced that interim data from the trial with children ages 2 to 4 found that two doses of a 3-microgram vaccine (a tenth of the dose given to adults) did not produce the same level of immune responses seen in people ages 16 to 25, for which the vaccine is already approved. According to unnamed officials who spoke with The New York Times, the two doses only generated 60 percent of the targeted level of antibodies against the pandemic virus. As such, the companies planned to add a third dose to be given at least two months after the second.

Dashed hopes

But late last month, as the ultra-transmissible omicron variant bore down on the US, the companies and the FDA seemed to shift their thinking. News broke that the FDA had encouraged Pfizer and BioNTech to submit data on just the two doses for children under 5. At the time, Scott Gottlieb, a former FDA commissioner and a current Pfizer board member, argued in an interview on CBS's Face the Nation that the two-dose vaccine may still provide protection from severe outcomes from COVID-19 and could get a regulatory green light to provide that "baseline" protection right away. A third shot to boost effectiveness against infection could be added later. The FDA statement today echoes that thinking: "The goal was to understand if two doses would provide sufficient protection to move forward with authorizing the use of the vaccine in this age group." But based on the reversal, the latest omicron data in children seems to have shifted the thinking again, with the FDA statement saying that, "at this time, we believe additional information regarding the ongoing evaluation of a third dose should be considered." Pfizer emphasized in today's press release that it is still hopeful a third dose will prove effective. The company notes that such thinking is "supported by recent observations of three-dose booster data in several other age groups that seems to meaningfully augment neutralizing antibody levels and real-world vaccine protection for omicron compared to the two-dose regimen." The FDA noted that it is postponing a meeting of its panel of expert advisers, which was planning to gather next week to review the two-dose data. "In the meantime, the best way to protect children, including when they are at school or daycare, is to practice social distancing and masking in accordance with public health recommendations and for their family members and caregivers to get vaccinated or receive a booster dose when eligible," the FDA statement concluded.