Which vaccine will work in youngest kids? Sharon LaFraniere and Noah Weiland
WASHINGTON — Over the past 10 months, as tens of millions of children and teenagers received the Pfizer-BioNTech vaccine, the companies’ main rival, Moderna, sat on the sidelines, its shot limited to adults.
But Moderna may now be poised for a comeback at a critical juncture in the nation’s vaccination campaign. The company is expected to send federal officials initial data this week on how well its coronavirus vaccine works for the nation’s youngest children.
About 18 million children younger than 5 are the only Americans not yet eligible for vaccination. And while uptake for older children has been slow, many parents are still anxiously awaiting the chance to protect their babies, toddlers and preschoolers.
Moderna is going head-tohead with Pfizer-BioNTech for the opportunity to vaccinate this group, hoping it has found what some scientists are calling the “Goldilocks” dose: strong enough to offer lasting protection, but not so strong that it causes widespread worrisome side effects, such as high fevers.
Moderna has opted for a regimen of two doses at one-quarter the strength of its adult dose for children younger than 6. Pfizer is expected to seek authorization next month for a threeshot regimen for children younger than 5, with doses one-tenth as strong as those for people ages 12 and older.
Moderna is also expected to release data soon from its clinical trial on the next age group up: children ages 6-11.
Dr. Yvonne Maldonado, a Stanford University professor of pediatric infectious diseases and a lead investigator at the Stanford site of Pfizer’s pediatric vaccine trials, said new data from Moderna and BioNTech in the coming weeks will offer critical insight into the effectiveness of their pediatric shots. She said researchers were watching carefully to see if Moderna’s stronger doses “result in more robust immune responses” than Pfizer’s shots in young children.
A series of new studies raising questions about how long Pfizer’s lower doses protect elementary-school-age children has piqued interest among federal scientists and vaccine experts in Moderna’s choices.
Dr. Ofer Levy, a pediatric expert at Harvard Medical School and a member of the Food and Drug Administration’s independent vaccine advisory committee, said he thought Pfizer might have selected too low a dose for 5to 11-year-olds “in the understandable priority to maximize safety.”
To date, Pfizer has been the only player in vaccinating younger Americans, winning authorization to vaccinate 12- to 15-year-olds in May, followed by 5- to 11-year-olds in October.
Moderna sought authorization to vaccinate teenagers in June, but the FDA delayed considering the request because of concerns about the risk of myocarditis, a condition involving inflammation of the heart that has been tied to both the Moderna and the Pfizer shots.
More than 22 million people in the U.S. younger than 18 are now fully vaccinated with the Pfizer vaccine, but uptake has been leveling off. Only roughly 1 in 4 children ages 5-11 are fully vaccinated, for example, even though shots have been offered to that group for more than four months.
But there is still a demand to protect the youngest children as more of the country unmasks, more parents return to workplaces and the summer travel season approaches.
Compared with adults, “there is no question that in children the benefit of an effective vaccine is less, because fewer get really sick,” said Dr. Eric Rubin, an infectious disease expert at Harvard and a member of an advisory panel to the FDA.
“But it will benefit some individuals,” he said. “It will save some lives.” According to the Centers for Disease Control and Prevention, 336 children in the U.S. younger than 5 have died of COVID-19.
Hopes that the youngest children would soon be covered surged last month after regulators pressed Pfizer-BioNTech to submit preliminary results from its three-dose trial. The FDA wanted to get the vaccination campaign underway with two doses while awaiting final results on three.
But that effort collapsed when new data from Pfizer that encompassed more of the omicron surge showed convincingly that two doses failed to protect adequately against symptomatic infection.
Now, more detailed results from Pfizer’s and Moderna’s trials are materializing at roughly the same time. And while neither company knows yet whether its vaccines will prove effective enough for the youngest age group, both say their research shows they are safe.