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What’s the timeline for kids under 5 to get a COVID vaccine?

Pfizer reports that a lower dose of its COVID-19 vaccine did not produce a potent immune response in children 2 to 4. Here’s what we know.

Kids as young as 5 can now get vaccinated against COVID-19. But what’s the timeline for children under 5?

On Friday, Pfizer-BioNTech announced data from its ongoing trial of children 2 to 4 indicates that the vaccine dosage used — 3 micrograms, or one-tenth of the adult dose — did not produce a potent immune response in that group after two shots. But the two-shot regimen did produce a response — comparable to the one seen in 16-to-25-year-olds — in infants between 6 months and 2 years old. Children 5 to 11 receive a 10-microgram dose, or one-third of the formulation for people 12 and older.

Pfizer said it did not plan to test a higher dose for children under 5 at this time but will test trial subjects’ immune response after administering a third dose.

“The goal here is to understand the potential of protection of the third dose,” Jerica Pitts, a spokeswoman for Pfizer, told the New York Times. “We are studying 3 micrograms at this time.”

Dr. Leian Chen, the lead physician at UCLA Health Pediatrics in Marina Del Rey, says she has conversations about vaccination daily.

“I have some families who will very eagerly ask every visit” about when their younger kids might be able to get vaccinated, she said.

Elementary-age children have been eligible for vaccination since early November, when the CDC gave emergency use authorization to Pfizer’s vaccine for kids 5 to 11. The American Assn. of Pediatrics reported that more than 7 million children have had COVID in the U.S. since the start of the pandemic, representing 17.2% of cases overall.

But progress has been slow: Since vaccines became available to that age group, the L.A. Times vaccine tracker indicates, only 22% of eligible children have received at least one dose in California — far behind the overall state vaccination rate of 73.6%.

What’s the status on vaccines for kids under 5?

This summer, Pfizer and Moderna said trials were underway for COVID vaccines for kids as young as 6 months. In a November email to The Times, in response to a query about the timeline for children under 5, Pfizer representative Kit Longley said, “We expect initial data for children 2 through 4 as early as [the fourth quarter of 2021] and data for children under 2 likely in the beginning of next year.”

Friday’s announcement indicates that timeline is still on track, though now Pfizer is testing a third dose of its mRNA vaccine for the 2-to-4 age group and observing and analyzing that data before applying for an emergency use authorization. “If the three-dose study is successful,” the company said in a news release, “Pfizer and BioNTech expect to submit data to regulators to support an Emergency Use Authorization (EUA) for children 6 months to under 5 years of age in the first half of 2022.”

Pfizer reported its vaccine for children 5 to 11 was safe and effective in late September and filed for emergency use authorization on Oct. 7. That EUA was granted Nov. 2. That’s similar to the timeline for the adult vaccine, which was granted emergency use authorization three weeks after Pfizer filed for it. So if you were to use previous timelines as an indicator, you would expect emergency use authorization about a month after the request is submitted.

What about Moderna and Johnson & Johnson?

Only adults 18 and older are eligible to receive Moderna’s two-dose mRNA vaccine and the one-dose Johnson & Johnson vaccine in the United States. Moderna has filed an EUA application to be able to vaccinate adolescents 12-17. A representative Moderna said in an email that the company is delaying filing a request for emergency use authorization for 6-to-11-year-olds while the FDA reviews the 12-to-17 data.

An emailed statement from Johnson & Johnson said Phase 2 and 3 clinical trials were underway in adolescents 12 to 17.

Meanwhile, the CDC has recommended that most eligible Americans opt for one of the mRNA vaccines instead of the Johnson & Johnson shot.

The winter outlook and safety

Chen, the pediatrician, said she expects to see more COVID-19 cases in children in the coming weeks.

“We’ve seen that kids definitely do get COVID. And fortunately, most are OK,” she said. “But some do get severely ill. And others do have long COVID symptoms.”

She said she fields questions from parents about the long-term safety of these vaccines and reports of side effects like myocarditis. She has personally reviewed the data, for both her patients and herself. Her 7-year-old became eligible for vaccination along with millions of other children this fall. She decided to get him vaccinated.

This story originally appeared in Los Angeles Times.