Pfizer-BioNTech shot for children under 5 safe and effective, FDA staff says

The analysis by FDA scientists was released ahead of a meeting Wednesday of the agency’s independent experts, who will consider a request for emergency use authorization for the Pfizer-BioNTech vaccine in the youngest children. It will also review a request from Moderna to use its vaccine in children younger than 6. FDA staff Friday said Moderna’s shot for infants and young children was safe and effective.

After the advisers make their recommendations, the FDA will decide whether to follow the panel’s advice, which it often does. If the agency clears the vaccines, and the Centers for Disease Control and Prevention signs off, the shots could be available beginning next week.

The FDA said the Pfizer-BioNTech vaccine met the main requirement for effectiveness — it generated an immune response at least as strong as the protection afforded to young adults from the vaccine.

Overall, the agency said, preliminary data indicated the vaccine was 80.4 percent effective in preventing symptomatic covid-19. The rate was 75.6 percent for babies and toddlers six to 23 months old, and 82.4 percent for children 2-to-4-years-old.

But the FDA said it was too soon to reach “definitive conclusions” on the vaccine’s effectiveness.

Side effects were minimal and included irritability and drowsiness for children 6-to-23-months-old, and pain at the injection site and fatigue for children 2 to 4, the FDA said.

Babies and children younger than 5 — a group numbering 19 million — remain the only age group in the United States not yet eligible for a coronavirus vaccine.

Some parents have been eagerly awaiting vaccines for their young children, anxious to provide them the same protection that older children, teenagers and adults have had for some time. But surveys show most parents intend to wait before getting their children vaccinated, or are not interested in the pediatric vaccines.

The FDA made clear Sunday it believes vaccines for the youngest group are critical. Given the uncertainty of the pandemic and likely continued virus transmission in coming months, “deployment of the vaccine for use among children 6 months through 4 years of age will likely have a beneficial effect on COVID-19 associated morbidity and mortality in this age group,” the agency said.

Pfizer-BioNTech’s vaccine trial consisted of two groups of children — 6-to-23-months-old and 2-to-4-years-old. The first two shots were administered three weeks apart, and the third was given at least eight weeks after the second dose. Each of the three doses is three micrograms, one-tenth of what adults get.

For many children, the gap between the second and third shot was significantly longer than the eight weeks set by the protocol. For children 2-to-4-years-old, the median interval between the second and third shots was 10.7 weeks. It was 12.9 weeks for the younger children.

Assuming both the Pfizer-BioNTech and Moderna vaccines are cleared, parents and pediatricians will have a choice. Some might prefer the Pfizer-BioNTech vaccine because of preliminary indications that it is more effective. But the three-shot regimen takes longer to complete than Moderna’s two-shot series, which might discourage some parents. On the other hand, the Moderna vaccine tends to cause more fevers, the data shows.

Most children are expected to get their shots in pediatricians’ offices but states and communities also are planning vaccine clinics, and some pharmacies will administer shots. Some sites will offer both vaccines, but many pediatricians’ offices say they will provide just one.

Sallie Permar, an expert in pediatric vaccines at Weill Cornell Medicine in New York, said her facility will offer both.

“While there may be some confusion, it gives you more flexibility,” Permar said. “Parents can weigh all the information and decide.”

On Friday, the FDA said the Moderna two-shot regimen produced the required immune response. The vaccine was shown to be 51 percent effective in preventing illness in children between 6 months and 2 years old, and 37 percent effective in children 2-to-5-years-old.

Vaccines for young children have followed a twisting — and often confusing — path, marked by disappointing results, delays and changes in regulatory strategies.

Pfizer and BioNTech initially tested a two-shot vaccine regimen but announced last December that the approach failed to meet the immune-response goal for the 2-to-4-year-old group. The vaccine makers added a third shot to their trial, delaying vaccine availability by months.

But in late January, federal officials made the surprising suggestion that there might be a path forward for the two-dose regimen, despite the disappointing results. They said that even if the vaccine missed the immune response target, which is measured in the laboratory, the vaccine still might protect children from infections.

But that data turned out to be disappointing, too, with only 28.3 percent effectiveness, according to the most recent figures, reflecting the emergence of the omicron variant of the coronavirus. The FDA dropped the plan to accelerate the vaccine and decided to await results from a third dose.