Coronavirus vaccine for young children further delayed as FDA says it will wait for data on three doses

The agency said it would not proceed with authorizing two doses of the Pfizer-BioNTech vaccine for young children after data from a trial showed it did not generate strong protection.

“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 agency said in a statement.

Pfizer and its partner, BioNTech, said they would have data on the three-dose regimen in early April. The delay is sure to be a bitter disappointment to the many parents who have been waiting anxiously for inoculations for children younger than 5.

“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 companies said in a statement. “This is also 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.”

Late last month, the FDA asked the vaccine makers to submit data for the two-dose regimen for young children. The idea was for regulators to start reviewing the information in hopes that a two-shot vaccine would be at least somewhat beneficial, and to issue an emergency use authorization for the shots. Officials indicated at the time that accelerating the process meant the vaccine could be available by the end of February.

It was widely expected that once the data on third shots became available, the FDA would authorize the vaccine as a three-dose regimen.

People familiar with the process said at the time that it was important to speed up the process as much as possible to offer protection to the youngest children. And the individuals, who spoke on the condition of anonymity to discuss internal deliberations, said there were indications the two-dose vaccine might be efficacious. The data showed the vaccine is extremely safe, they said.

But a close review of additional data, which concluded Friday, showed that the two-dose regimen was not protective, the agency said. The FDA decided to postpone an expert advisory panel meeting that had been scheduled for Tuesday to scrutinize the vaccine’s performance in children.

Friday’s action is the latest twist in the saga of the long-awaited pediatric vaccine. In December, Pfizer and BioNTech, announced that the immune response generated by the vaccine in children between 2 and 4 years old was not sufficiently robust. The vaccine did provoke a strong enough response in children 6 months to 2 years old. A third shot was added to the trial to increase the immune response.

When the FDA decided to ask the companies for the two-shot information, FDA spokeswoman Stephanie Caccomo said in an email that the surge in cases related to the omicron variant of the coronavirus had generated data “impacting the potential benefit-risk profile of a vaccine for the youngest children.”

“In light of these new data and the rise in illnesses and hospitalization in this youngest age group, FDA believed that it was prudent to request that Pfizer submit the data it had available, including the data that it has recently collected during the omicron surge,” Caccomo said.

The vaccine trial was designed primarily to measure whether children’s immune systems mustered a response similar to the one that protected older teens and adults from getting sick. There were about 3,900 children between 6 months and 4 years old enrolled in the trial as of Jan. 20.

Third shots only started on Jan. 31, according to a presentation during Pfizer’s quarterly earnings call, so data is still being collected.