Moderna’s latest COVID vaccine trial for kids offers ‘really good news’

No COVID vaccines are available to the youngest children, but vaccine makers aim to change that soon.
moderna covid shot
Moderna says new COVID vaccine clinical data show protection for children as young as 6 months. Unsplash

Moderna’s COVID-19 vaccine is safe and effective in children aged 6 months to 5 years old, the vaccine maker said Wednesday, citing a newly completed Phase 2/3 study. The company hopes the Food and Drug Administration will soon authorize emergency use of its vaccine in that age group.

In the randomized, observer-blind, and placebo-controlled trial, 2,500 children ages 6 months to 1 year and 4,200 children ages 2 to 5 were given two doses of Moderna’s mRNA vaccine. Each shot was 25 micrograms, administered 28 days apart. Adults receive two shots of 100 micrograms each, by comparison. The company said in a statement that vaccine efficacy was 43.7 percent in children 6 months to 2 years and 37.5 percent in the 2 to under 6 years age group, with “a favorable safety profile.” 

While the vaccine efficacy percentages seem low, Moderna said in a statement that they are on par with what would be expected of a two-dose vaccine against the Omicron variant, which was the most prevalent variant at the time of the trial. None of the vaccinated children experienced severe disease, hospitalization, or death. Seventeen percent of 6-month to 1-year-olds and 14.6 percent of 2- to 5-year-olds experienced fevers greater than 100°F, but those rates are comparable to other pediatric vaccines.

“We believe these results are really good news for the parents of children who are under 6 years of age, and for the children themselves,” Jacqueline Miller, senior vice president of infectious diseases at Moderna, told The Wall Street Journal. “We are hopeful to be able to bring this vaccine forward to address that unmet medical need.”

[Related: A deep dive on the evolution of COVID and its variants]

There is no vaccine authorized for emergency use in children under the age of 5. For kids ages 5 through 11, the FDA has authorized Pfizer-BioNTech’s vaccine. But the youngest members of the population still remain unprotected.

Vaccinating the youngest cohorts of our population “has been somewhat of a moving target over the last couple of months,” Bill Muller, an investigator in Moderna’s pediatric studies, told The Associated Press. “There’s still, I think, a lingering urgency to try to get that done as soon as possible.”

“A [vaccine efficacy] of 40 percent with adequate safety data could be very meaningful, especially to higher risk individuals,” Luciana Borio, a former FDA acting chief scientist who is now a partner at Arch Venture Partners, told STAT News

While having an available vaccine for the youngest kids will provide huge relief for some, evidence shows that most parents won’t seek shots for their young kids right away. A Kaiser Family Foundation poll shows that as of February 2022, only 21 percent of parents of children under 5 say they’ll vaccinate their kids right away. Twenty-six percent say they plan to “wait and see,” 15 percent say they will vaccinate their kids only if required, while 35 percent say they definitely will not. 

Unlike Pfizer’s vaccine, Moderna’s vaccine has not yet been approved for use in children ages 6 through 11. The FDA has also been delaying its decision to approve the Moderna vaccine for teens aged 12 through 17—the agency says it is evaluating the potential risk of dangerous side effects, like myocarditis. Moderna said in its statement that it will be resubmitting the request for emergency use in this age group while providing additional follow-up data. Moderna also plans to test a booster dose for all child populations.