Scientific advisors from the Centers for Disease Control and Prevention began meeting Saturday to decide whether the benefits of Covid vaccines outweigh the risks for children under age 5, one of the last groups of Americans to qualify for the vaccines.
The meeting, which is being broadcast live here, began at 10 am ET. Advisers are expected to vote yes, despite reservations about the paucity of data, especially on the effectiveness of the Pfizer-BioNTech vaccine.
Earlier this week, another panel of experts advising the Food and Drug Administration unanimously supported the vaccines. The FDA on Friday authorized the Moderna vaccine for children ages 6 months to 5 years and the Pfizer vaccine for children ages 6 months to 4 years. (The Pfizer-BioNTech vaccine has been available for children ages 5 and older since November.)
On Friday, CDC advisers heard evidence supporting the effectiveness of vaccines in younger children. But the committee repeatedly pressed Pfizer on its estimates and noted that it would take three doses of this vaccine to protect children, compared with two doses of the Moderna vaccine.
Both vaccines are safe and both produced antibody levels similar to those seen in young adults. If the committee’s endorsement on Saturday is quickly followed by a green light from the agency’s director, Dr. Rochelle Walensky, states are getting ready to start immunizing children next week.
Among the tasks facing the CDC panel on Saturday is the difficulty of recommending two very different vaccines for the same population.
“Implementing these two launches will be incredibly challenging,” said Katelyn Jetelina, public health expert and author of the widely read newsletter “Your Local Epidemiologist.”
“There’s going to have to be a lot of proactive communication about the difference between the two and the implications of taking one over the other,” she said.
In its clinical trials, Moderna found that two injections of its vaccine, each a quarter of the adult dose, produced antibody levels at least as high as those seen in young adults.
The company estimated the vaccine’s effectiveness against symptomatic infection at about 51% among children aged 6 to 24 months and 37% among children aged 2 to 5 years. Side effects were minor, although about one in five children had a fever.
Based on these data, the FDA authorized two injections of the Moderna vaccine, four weeks apart.
The Pfizer-BioNTech vaccine also produced a strong immune response, but only after three doses, company officials told scientific advisers on Friday.
Two doses of the vaccine were inadequate, they said — justifying the FDA’s decision in February to delay authorization of the vaccine until regulators had data on three doses. Two doses may not have been enough because the company gave children only a tenth of the adult dose with each injection, some consultants said.
The vaccine has an overall effectiveness of 80% in children under age 5, Pfizer scientists said Friday. But that calculation was based on just three children in the vaccine group and seven who received placebo, making it an unreliable metric, CDC advisers noted.
“We should just assume that we don’t have efficacy data,” said Dr. Sarah Long, an infectious disease specialist at Drexel University School of Medicine. But Dr. Long said she was “comfortable enough” with other data proving the vaccine’s potency.
Three doses of Pfizer’s vaccine produced antibody levels comparable to those seen in young adults, suggesting it is likely to be equally effective.
“Pfizer is a three-dose series, but as a three-dose series, it is quite effective,” said Dr. William Towner, who led vaccine trials for Moderna and Pfizer at Kaiser Permanente in Southern California.
Any vaccine would be better than none, added Dr. Towner. He predicted that some parents might opt for Moderna because taking children to the pediatrician for two injections is easier than arranging for them to get three shots.
Pfizer’s vaccine was authorized for children ages 5 to 11 in November, but less than 30% of that age group received two injections. Parents of younger children may be more willing to opt for a Covid vaccine if it can be offered alongside other routine immunizations, Towner said.
“That’s the area that a lot of people aren’t sure about right now,” he said. “I hope there is some guidance offered around that.”