What we know about the COVID-19 vaccines for kids under 5

The youngest people are still ineligible for the shots. Vaccine manufacturers and families hope that will change soon.

A child receiving her COVID-19 vaccine.NICOLAS MAETERLINCK/BELGA MAG/AFP via Getty Images

Time and time again, New England states are among the most protected against COVID-19.

Over 70 percent of Massachusetts residents are armed with a full vaccine regimen. Two million people here have received an additional booster shot. In addition, Boston, Salem, and Brookline have enacted proof-of-vaccination mandates for indoor spaces, in an effort to use immunizations as a community weapon against the Omicron variant and rising case numbers.

But the youngest people remain ineligible for the shots. None of the three approved vaccines in the United States are authorized for children under 5. And that has some parents anxious.

Here’s a rundown on the path to vaccines for this age group — and why they’re stalled.

What clinical trials are underway?

Pfizer-BioNTech and Moderna are conducting clinical trials for children 6 months to 4 years old.

As of now, only the Pfizer vaccine is available to Americans between the ages 5 and 17. The Centers for Disease Control and Prevention recommends that children older than 12 also receive a Pfizer booster dose, at least five months after their second shot.

Johnson & Johnson has not started trials of its vaccine for children younger than 12. (In December, the CDC released guidance that suggested people choose the mRNA vaccines over J&J’s one-shot option.)

How long will it be until the vaccines are authorized?

The hope for manufacturers (and many families) is early 2022.

In a December earnings call, Pfizer executives said they expect to submit trial data to regulators in the first half of the year. On the Moderna vaccine, Dr. Bill Hartman, who runs the company’s vaccine trial for kids 6 months to 5 years at the University of Wisconsin-Madison, told CNN last month that he thinks shots could be available as early as the next month.

The Pfizer trial suffered a setback in mid-December when the company announced that its two-dose vaccine regimen performed poorly against the virus in preschool aged children.

The company had tested 3 micrograms of the vaccine — one-tenth of the adult dose — in trial participants. After two doses, children between 6 months and 2 years did produce a protective immune response. But children between 2 and 5 years old did not.

Pfizer then amended its research to include a third dose for kids 4 and younger.

Stéphane Bancel, the chief executive at Moderna, said earlier this week that the company’s data for testing on younger children is imminent. But it is unclear when a vaccine would be ready.

What’s next?

Once the regimen is tweaked to adequately protect children under 5, manufacturers will be subject to an authorization process that involves the Food and Drug Administration and the CDC — a path that every other vaccine measure followed last year.

The FDA will be charged with issuing an emergency authorization. The decision will then be weighed by a CDC advisory committee and its director, Dr. Rochelle Walensky.

If approved, the fate of the vaccines rests with the companies and their ability to distribute doses to pharmacies and clinics nationwide. In the past, vaccine administration sites have been quickly stocked after an authorization announcement.

Are kids at-risk of getting COVID-19?

Children make up a small fraction of COVID cases and hospitalizations.

That said, pediatric hospitalization is at now its highest rate since the start of the pandemic, according to the CDC. Among children, those under 5, who are ineligible for the vaccine, are most likely to be hospitalized.

“Most of these hospitalizations are because of COVID-19, although some are children who were admitted for other causes but tested positive for COVID-19 when they were admitted or during their hospital stay,” the CDC wrote.

In Massachusetts, schools saw record-breaking case numbers among students and staff earlier this month. State education leaders reported 41,063 new COVID-19 cases among public school students and 7,351 cases among staff members for the week that ended Wednesday. The total number of cases, 48,414, represents a drop of 2,686, or about 5 percent, from those reported the previous week.

Still, children are far less likely to die from the virus. They make up less than 1 percent of US deaths, the CDC found.