Pfizer Delays FDA Request for COVID-19 Vaccine for Children Under 5

Pfizer announced on Friday plans to delay its application to the FDA for approval of its COVID-19 vaccine for children under the age of 5. The company was set to meet with the FDA on February 15 but postponed the meeting to gather more clinical trial data for a three-dose regimen as opposed to its previously proposed two-dose schedule. Based on the results of the trials involving two doses, Pfizer believes a third dose will provide a more robust immune response in young children.

This news comes as a setback to parents of young children eagerly awaiting the chance to vaccinate their children. The FDA approved Pfizer’s COVID-19 vaccine for 12-15-year-olds in May 2021 and approved its vaccine for 5-11-year-olds in late October of 2021. There is no COVID-19 vaccine currently available for children under the age of 5.

For months, parents of babies, toddlers, and preschoolers hoped for reassurance their children would be protected from the most severe outcomes of COVID-19, especially as hospitalizations of young, unvaccinated children spiked during the Omicron surge.

Pfizer's COVID-19 Vaccine Trial for Kids Under 5

Due to the spike in infections during the Omicron surge in early February, the FDA requested that Pfizer submit its trial data for Emergency Use Authorization (EUA) of the vaccine in young kids. The idea was that the two-dose vaccine could be given to 2- to 4-year-olds now, with the hopes of offering a third shot for optimal protection once the trial data became available.

However, this plan changed because Pfizer's three-dose trial was moving faster than expected. They were confident they would have the trial data in a shorter time frame, and that the data would show a stronger and more protective immune response.

"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," Pfizer stated in its press release.

The change in plans does not mean there are problems with the vaccine, says Zachary Hoy, MD, a pediatric infectious disease specialist at Pediatrix Nashville Pediatric Infectious Disease. Rather, researchers want to make sure the vaccine is as effective as possible. The first vaccine tests looked at two different cohorts: babies ages 6 to 24 months, and young children ages 2 to 4. Each age group was given a 3 µg dose of the Pfizer vaccine in two separate doses, spaced 21 days apart.

This was a smaller dosage than the dose given to 5- to 11-year-olds (10 µg) and the dose given to 12-to 15-year-olds (30 µg). For the 3 µg dose, there were no safety concerns for either the 6- to 24-month group or the 2 to 4 age group.

According to Pfizer, a 3 µg dose of vaccine was able to produce a robust immune response in babies similar to the immune response the vaccine produced in 16- to 25-year-olds. However, the immune response in 2- to 4-year-olds was not as robust. Pfizer paused the trial to test a third 3 µg dose in the 2- to 4-year-old cohort to see if it produced stronger results. Pfizer says it plans to gather new data quickly and should have the results of the three-dose trial available by early April 2022.

“The trial was originally halted because the lower COVID-19 vaccine dose in this age group was not creating a level of antibody protection seen in other vaccines,” Dr. Hoy explains. “Pfizer wanted to make sure children would have similar protection to other groups with vaccination but also have a safe dose.”

The Importance of a COVID-19 Vaccine for Kids Under 5

Although Pfizer pushed back its vaccine application, the need for a vaccine for younger kids continues to be pressing, experts say. Although COVID-19 is usually mild in children, severe outcomes are possible, especially in children who have not been vaccinated. This was seen during the Omicron surge in New York, where the New York State Department of Health reported a substantial increase in pediatric hospitalizations.

New York City alone saw an 18-fold increase in COVID-19 hospitalization among children. Across the state, the majority of admitted children were unvaccinated. In fact, 55% of hospitalized children were under the age of four, a population that was ineligible for vaccination at the time.

Having a vaccine for young kids will help reassure parents that their children will be spared the possibility of a severe outcome, should they contract the virus. Before, this reassurance was only available for kids 5 and up.

“Approval of this vaccine would mean almost all members of a household could be vaccinated against COVID-19, with the exception of young infants under six months of age,” says Dr. Hoy.

Additionally, young children saw a major spike in infections during the Omicron surge, and as a result, parents had to deal with daycare and preschool closures, quarantines, and isolation periods. All of these were very disruptive to both parents and their kids. Preeti Parikh, MD, a pediatrician and the executive medical director at GoodRx, is hopeful that the approval of this vaccine will make life a little easier for parents of young kids.

“A vaccine allows children to get back to a more normal life,” Dr. Parikh. “They can attend daycare, preschool, classes, travel, and birthday parties, and it helps decrease the quarantines and disruptions COVID-19 has caused in their lives and their family’s lives.”