FDA Authorizes COVID-19 Vaccines for Children as Young as 6 Months

The Food and Drug Administration (FDA) on Friday authorized the Pfizer and Moderna COVID-19 vaccines for emergency use in children as young as 6 months, more than a year after authorizing the shots for adults.

The authorization was followed by support from the Centers for Disease Control and Prevention (CDC) on Saturday, meaning vaccination can begin in young children. So far, all states besides Florida have preordered vaccines for young children.

Earlier this week, an FDA advisory panel voted unanimously to recommend the Pfizer shot for children 6 months through 4 years, and the Moderna shot for those 6 months through 5 years.

During the two-day meeting, panelists emphasized the clinical and social benefits of vaccinating children against COVID-19, both for their health and for society at large.

“I know that the death rate from COVID in young children may not be extremely high, but it’s absolutely terrifying to parents to have their child be sick and have to go to the hospital,” said Jay Portnoy, MD, a professor of pediatrics at Children’s Mercy Hospital in Kansas City, Mo.

Vaccinating the Youngest Children

The FDA panelists emphasized that children can get seriously ill and be hospitalized from COVID-19. Cases and hospitalizations among infants and young children increased alongside adults during the Omicron wave. Throughout the pandemic, roughly one in four children required ICU admission.

While some panelists emphasized that the risk of death from COVID-19 is relatively low, others applauded the ability to offer a vaccine option for children, especially those who are most vulnerable to severe illness from COVID-19.

Both vaccines appear substantially less effective at protecting against COVID-19 than the vaccines authorized for adults. But the companies and regulators said much of the difference was due to the ability of Omicron and its subvariants to evade immune defenses.

For each of the vaccines, panelists said it’s likely that an additional dose will be required to protect against future variants. This means Moderna recipients may need three shots to be fully protected and Pfizer vaccinees may eventually need four.

The manufacturers each tested several dose sizes to minimize the risk of fever and other side effects in kids. Pfizer landed on a dose that is just a tenth of the strength given to adults, and Moderna chose a dose a quarter the strength of its adult vaccine.

Pfizer’s Efficacy & Safety Data

Pfizer initially asked the FDA to authorize a two-dose series. But the company also presented data on a three-dose primary series and the panelists agreed that the vaccine regimen should include all three shots.

A two-dose primary series elicited an immune response in nearly all the children during trials, but it was only about 22% effective at protecting against infection during the Omicron wave.

Paul Offit, MD, a panelist and director of the Vaccine Education Center at Children’s Hospital of Philadelphia, called the data “surprising.”

“It does worry me actually that there was no protection after dose two,” he said.

Adding a third dose boosted efficacy to about 80%, according to additional data presented by Pfizer officials. But that data was based on about cases in only three vaccinated and seven placebo participants.

Besides, some panelists questioned the feasibility of asking parents to have their kids vaccinated three times. Allowing children to be vaccinated against COVID-19 at the same time as other routine childhood vaccinations could help, but Pfizer hasn’t collected data about how this would influence vaccine efficacy.

“For people who have gotten two doses of that vaccine, they have to know they’re not protected,” Offit said. “I wonder whether parents will understand that.”

Amanda Cohn, MD, a top CDC official and panelist, questioned how long the interval should be between the second and third doses. Pfizer officials suggested it should be eight weeks, although the study participants had a median of 13 weeks between shots.

Doran Fink, MD, PhD, acting deputy director of the FDA’s vaccine division, said that Pfizer’s data is enough to conclude that the benefit of vaccinating this age group outweighed the risks. But he said he considered the data to be “imprecise and potentially unstable.”

“In terms of what the efficacy is after a third dose and whether an additional dose beyond that is needed will require more data,” Fink said.

Moderna’s Efficacy & Safety Data

Moderna’s vaccine for infants created antibody levels similar to those observed in teens and young adults, but lower than seen in older children. However, Moderna collected data for the youngest age group during the Omicron wave, while the older children were vaccinated before the variant was dominant.

The two-dose vaccine was 50.6% effective for infants 6-23 months old and 36.8% effective for kids 2 to 5 years old. The company said this is on par with the protectiveness of vaccines in adults infected with Omicron.

Jacqueline Miller, MD, senior vice president at Moderna called the data on Moderna’s vaccines “remarkably consistent across age groups,” despite the lower dosage for younger children.

Moderna is also currently testing boosters for this age group. Miller said the company is in the final stages of planning a study of its vaccine in children 3 months to 6 months old.

It’s Up to Parents to Make Vaccine Decisions

Some parents remain resistant to having their children vaccinated. In a Kaiser Family Foundation poll from April, one in five parents of children younger than 5 said they are eager to have their child vaccinated right away. About 4 in 10 said they would “definitely not” have their child vaccinated, or would only do so if required.

Despite the unanimous votes to authorize the vaccines for toddlers and infants, panelists were divided on how important vaccination for kids is.

Cody Meissner, MD, a professor of pediatrics at Tufts University, compared the chance of a young child dying from COVID-19 to that of getting struck by lightning. Other panelists urged their colleagues not to downplay the significance of COVID-19 as a pediatric disease with far-reaching consequences.

“There are so many parents who are absolutely desperate to get this vaccine,” Portnoy, a pediatrics professor, said. “I think we owe it to them to give them the choice.”

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