C.D.C.’s Advisers Debate Vaccines for Youngest Children

Almost exactly 18 months after the first coronavirus vaccine was authorized for adults, and after months of scientific hiccups, the youngest Americans may finally get their shots.

Over discussions scheduled for Friday and Saturday, scientific advisers to the Centers for Disease Control and Prevention are debating the use of Moderna’s vaccine for children younger than 6 and Pfizer-BioNTech’s vaccine for those younger than 5. Neither vaccine is intended for infants younger than 6 months old. (Watch Friday’s meeting here.)

The Food and Drug Administration authorized the vaccines before the C.D.C. panel meeting began on Friday. Assuming the advisers back the vaccines, the C.D.C.’s director, Dr. Rochelle Walensky, is expected to sign off in short order. States have already acquired millions of doses and will be prepared to offer shots to children as early as Tuesday.

Pfizer’s vaccine has been available to children 5 to 11 years since November, but less than 30 percent of children in that age group have received two shots.

But the Omicron surge in the United States led to record numbers of hospitalizations and emergency room visits for children 6 months through 4 years, particularly among children of color, said Dr. Katherine Fleming-Dutra, a C.D.C. researcher who presented epidemiological data at Friday’s meeting. Those rates were higher than seen among older children.

More than half of the hospitalized children aged 6 months to 4 had no underlying conditions, she said.

The C.D.C. panelists spent considerable time on Friday morning trying to pinpoint how the Omicron variants have altered the risks to children. They noted that parents vaccinate their children for many other diseases with comparable, or even lower, risks of death.

The data “should just decimate the myth that this infection is not life-threatening in this age group,” said Dr. Sarah Long, a panelist and an infectious diseases expert at Drexel University College of Medicine.

Some experts drew parallels to influenza. Between October 2021 and April 2022, Covid-19 hospitalization rates were as high or higher than those for influenza in recent influenza seasons.

Between 63 percent and 75 percent of parents of children 6 months through 4 years of age chose to vaccinate their children against influenza, despite wide variability in the effectiveness of those vaccines, noted Dr. Matthew Daley, a senior investigator at Kaiser Permanente Colorado who leads the C.D.C.’s vaccine working group.

Unvaccinated people 5 and older had 10 times the risk of dying of Covid-19, compared with those who received at least two shots of the vaccine, Dr. Daley said. The figures “provide real world-evidence that most deaths from Covid-19 are preventable through vaccination,” he added.

Acceptance of the vaccines will depend partly on how clear the C.D.C.’s recommendations are. The F.D.A. authorization permits vaccines to be used, but doctors look to the C.D.C.’s advisory committee for specifics on how to use them.

This time around, that advice is likely to be complicated, because the two vaccines differ in almost every aspect.

For young children receiving the Moderna vaccine, the F.D.A. authorized two doses of 25 micrograms each, one-fourth the amount used for adults, spaced four weeks apart.

But according to the data presented on Wednesday to the agency, two doses of the Pfizer vaccine — each just three micrograms, or one-tenth of the adult dose — fell short of producing strong immunity against the virus in young children.

To be effective, the Pfizer vaccine will need to be administered in three doses: the first two spaced three weeks apart, and a third at least two months after that.

Some studies have suggested that the vaccines might work better if the interval between doses is extended, and the C.D.C. now says children 12 and older and younger adults at low risk of Covid-19 may consider getting their second dose of vaccine eight weeks after the first.

But the United States has not collected the information needed to determine the ideal interval for young children, Dr. Doran Fink, a senior F.D.A. official, said on Friday.

“We’re unlikely to get relevant data from the U.S., and so we will have to look at international real-world data,” he said.

The F.D.A.’s advisers on Tuesday also endorsed the use of Moderna’s vaccine for children aged 6 and older, but the C.D.C.’s committee has deferred that discussion until next Thursday.