Moderna Says Its COVID Vaccine Works in Kids Under 6

Elena Rosales gets applause while checking out her new Band-Aid after receiving her shot during Moderna’s COVID-19-vaccine trial on December 7, 2021. Photo: Brian Cassella/Chicago Tribune via Getty Images

In another step forward on the long road to a COVID-19 vaccine for young kids, Moderna announced on Wednesday that its vaccine generated a strong immune response in children 6 months to 5 years old. Interim results from Moderna’s clinical trial showed that this population had an immune response similar to what was observed in previous trials of young adults ages 18 to 25.

The trial uncovered no new safety concerns. The majority of side effects among the 6,700 participants under 6 were mild or moderate. “No deaths, no myocarditis or pericarditis, and no multisystem inflammatory syndrome in children (MIS-C) were reported,” the company said.

However, the regimen of two 25-microgram doses, a quarter of what adults receive, showed only modest effectiveness against COVID infection. The trial, which largely took place when Omicron was the dominant variant, showed that the vaccine’s efficacy against symptomatic infections was 43.7 percent in children 6 months to 2 years old and 37.5 percent in children ages 2 to 5. “The efficacy rates were lower than seen during adult testing, which took place before Omicron emerged, but comparable to the real-world effectiveness of two doses of Moderna’s vaccine found among adults during the Omicron wave,” The Wall Street Journal reported.

The majority of COVID cases in the pediatric trial were mild, Moderna said, and there were no cases that resulted in “severe disease, hospitalization, or death.”

Though children infected with COVID typically become less severely ill than adults, more than 1,000 children under 18 have died over the course of the pandemic, including 350 children under 5, according to CDC data. COVID’s long-term effects on children are still unknown.

Moderna said that, based on its current data, it expects to request Food and Drug Administration authorization of its two-dose vaccine for children 6 months to under 6 years “in the coming weeks.”

“Given the need for a vaccine against COVID-19 in infants and young children we are working with the U.S. FDA and regulators globally to submit these data as soon as possible,” said Moderna CEO Stéphane Bancel.

But the approval of a vaccine for children under 5 may still be a ways off. Last month, Pfizer and the FDA agreed to delay the company’s request for authorization of its pediatric vaccine after data collected during the Omicron surge showed the two-dose regimen was less than 50 percent effective against symptomatic disease. The New York Times reports:

Whether the Food and Drug Administration, the Centers for Disease Control and Prevention and the public will be willing to accept Moderna’s average efficacy rate of about 40 percent for children under 6 is unclear.

While Americans have been hearing for months that the vaccines are less potent against Omicron in all age groups, 40 percent is below what many vaccine experts consider the minimum standard for effectiveness against Covid disease. The standard initially set for adult coronavirus vaccines was at least 50 percent effectiveness against symptomatic infection.

Moderna said it is “preparing to evaluate the potential of a booster dose for all pediatric populations” but will seek approval for its two-dose regimen in the meantime. Pfizer is testing a third shot for children under 5 with results expected in early April. U.S. regulators may wait until that data is in so it can compare Pfizer’s three-dose and Moderna’s two-dose regimens before approving either vaccine for use in young children.