WASHINGTON — Moderna said on Wednesday it would seek emergency clearance for its coronavirus vaccine for children under 6 after interim results from its clinical trial showed volunteers in that age group had a similar immune response to young adults when given a dose of one: fourth so strong.
But the company said the vaccine was found to be only about 44 percent effective at preventing symptomatic disease in children 6 months to 2 years old, and 37 percent effective in children 2 to 5.
dr. Jacqueline Miller, the company’s senior vice president for infectious diseases, said the relatively low level of protection demonstrates the Omicron variant’s ability to evade the vaccine’s shield. Nevertheless, she said in an interview, “what we have seen is a successful trial.”
“What I will say is 37.5 percent and 43.7 percent is above zero,” she said. “If I were the parent of a young child, I wish there was some protection on board, especially if we see a new wave of infections.”
The company’s announcement comes as the Biden administration’s effort to protect people from an ever-mutating virus enters another period of change. Officials are debating whether the oldest Americans should at least get a second booster shot this spring. Meanwhile, several studies are trying to determine whether the existing vaccines can be reconfigured to provide greater protection against Omicron and the sub-variant of the virus known as BA.2.
Now, Moderna’s findings about how well the vaccine works in the nation’s youngest children — the only Americans not yet eligible for injections — raise another question: What level of effectiveness is good enough for a pediatric vaccine? ?
Last month, Pfizer and its German partner, BioNTech, postponed seeking emergency approval for their coronavirus vaccine in young children after data collected during the Omicron peak showed that two doses were less than 50 percent effective against symptomatic illness, according to people known. be with the situation.
Whether the Food and Drug Administration, the Centers for Disease Control and Prevention and the public will be willing to accept Moderna’s efficacy rate of about 40 percent on average for children under the age of 6 is unclear.
While Americans have been hearing for months that vaccines are less potent against Omicron in all age groups, neither Moderna nor Pfizer’s results in young children meet what many vaccine experts consider the minimum standard of effectiveness against Covid-19. The FDA’s initial guideline for adult coronavirus vaccines was at least 50 percent effective against symptomatic infection.
All three authorized vaccines — from Moderna, Pfizer, and Johnson & Johnson — greatly surpassed that initially. But Omicron’s uncanny ability to evade the immune system’s defenses alters the calculus, and no new standard has been set as of yet.
The FDA approved the Pfizer-BioNTech vaccine in May for individuals ages 12 to 15 after a trial showed zero infections in the vaccine arm and 18 in the placebo group — a ratio Pfizer described as 100 percent efficacy. But in October, when the agency approved Pfizer’s vaccine for children ages 5 to 11, it relied solely on immune response data, which showed the vaccine triggered a powerful surge of antibodies. That was also the criterion for the experiments with younger children.
At the time, given the antibody response, regulators were unwilling to wait for Covid infections to occur in enough trial participants to measure efficacy. But because the Omicron variant spread through such a large segment of the population during the winter, both Moderna and Pfizer can now measure the efficacy of their youngest trial participants.
Pfizer decided last month to postpone an emergency two-dose application after seeing efficacy data from the Omicron peak.
Moderna is asking for a similar authorization, citing equally weak efficacy data. On the other hand, Moderna’s two-dose regimen achieved better results than Pfizer’s in boosting the immune system of young children. Pfizer said in December that after two doses of its vaccine, children aged 6 months to 2 years produced antibody levels comparable to those seen in older teens and young adults.
But children ages 2 to 4 produced only 60 percent of the wanted antibody response. After two doses of Moderna’s vaccine, the antibody response of children in both subgroups compared favorably with those of people ages 18 to 25, meeting the primary criterion for success of the trial.
“I am encouraged by the strong neutralizing antibody response that indicates long-term cellular immunity,” says Dr. Monica Gandhi, infectious disease physician and professor of medicine at the University of California, San Francisco.
dr. Anthony S. Fauci, the White House chief medical adviser, said at a briefing Wednesday that Moderna’s shot proved safe for young children. While the efficacy rate “may seem like a low number,” he said, “in the era of Omicron, this is actually quite comparable to the efficacy against infection in what we’re seeing with other vaccines now.”
“So the data looks pretty good right now,” he said.
Pfizer has said it will have data on how well three doses work by early April. That could allow the FDA to compare the results of Moderna’s two doses and Pfizer’s three doses before approving either vaccine.
Nearly two-thirds of the US population, or more than 217 million people, has been fully vaccinated, and about half of those eligible for booster injections have received them. But progress in children is dragging on: Only about one in four of children between the ages of 5 and 11 are fully vaccinated.
So far, the Pfizer-BioNTech vaccine has been the only approved vaccine for those 5 to 18 years. But Stéphane Bancel, Moderna’s CEO, said in a statement on Wednesday that the company would also seek emergency approval for the injection in children ages 6 to 11. , and would update a similar request it made for those 12 to 17 last year.
That request was put on hold because the FDA wanted to see more data on a rare side effect, myocarditis, which involves inflammation of the heart. Moderna says those concerns have now abated, and at least some federal health officials agree.
Regulators don’t typically skip age groups when authorizing vaccines, so the FDA may consider allowing Moderna’s injections to infants through teens all at once.
About 6,900 children in the United States and Canada participated in Moderna’s trial for children under six. Moderna said there were no cases of serious illness, hospitalization or death. Most infections in the trial group were mild.
dr. Miller said Moderna was investigating whether a booster shot might be necessary for anyone under the age of 18. “We definitely plan to give these children a booster dose,” she said.
Most adverse events among trial volunteers were mild or moderate, and fever was typical of existing pediatric vaccines. Fourteen children – 0.2 percent of the study group – developed a fever of more than 104 degrees, the company said.
Young children generally do not become seriously ill from Covid. But according to a dataset released by the CDC, 355 children under the age of 5 have died of Covid since the start of the pandemic in the United States. CDC officials say data is most reliable because it’s based on death certificates; other estimates are higher.
There is clearly a demand to protect the youngest children, especially as more of the country unmasks the masks, more parents return to work and more normal life patterns resume.
dr. Caitlin Elgarten, a pediatrician in Philadelphia, included her 2-year-old son and 4-year-old daughter in Moderna’s trial. She anxiously awaits the results.
She said she was concerned about the potential of long-term Covid, with the lasting health consequences, if her children got sick. She also said the 10-day quarantine many nurseries are enforcing for infected children is “a huge burden on life and family.”
“It feels like the world goes on,” she said, “when we either have to accept the risk or keep limiting ourselves when no one else is.”
