Moderna’s coronavirus vaccine elicits a strong immune response in children aged 6 to 11, researchers reported Wednesday – another indicator of what has become a long and winding road to protect young children from the virus, even as cases rise again.
On Monday, Moderna sought clearance from the Food and Drug Administration for use of the vaccine in this age group. But the permission, if granted, is unlikely to greatly increase low vaccination rates among young children.
The Pfizer-BioNTech vaccine has been available for children aged 5 to 11 since November, but as of Wednesday only 28.7% had received two doses. There is no coronavirus vaccine available for children under 5, forcing parents to rely on less reliable protective measures.
Last month, Moderna asked the FDA to clear its vaccine for use in children 6 months to 6 years old. The agency is already reviewing the company’s data on adolescents and is expected to decide on the use of the Moderna vaccine in children of all ages in June.
In February, Pfizer and BioNTech also applied for authorization of their vaccine for use in younger children, but withdrew the application after data suggested that two doses did not produce adequate protection against the Omicron variant.
The companies are banking on a third dose to boost immunity in children, and the FDA is also expected to review that data in June.
“We really can’t do it this way in the future – we can’t leave the kids to last,” said Dr. Sallie Permar, pediatric vaccine expert at Weill Cornell Medicine in New York.
The process has been particularly confusing and unfair for parents of younger children, who still don’t have access to a vaccine more than two years into the pandemic, she said.
It’s been nearly a year since Moderna sought FDA clearance for the use of its vaccine in adolescents ages 12 to 17. While the agency greenlighted Pfizer-BioNTech’s vaccine for use in this age group in just three weeks, the agency’s review of Moderna’s vaccine stalled.
The clearance time was the longest in the United States. European medicines regulators approved Moderna’s vaccine for adolescents aged 12 to 17 last summer and recommended approval for children aged 6 to 11.
Regulatory agencies in Canada and Australia have also authorized the Moderna vaccine for ages 6 to 11.
In the United States, just over one in four out of 28 million children aged 5 to 11 have been vaccinated against the coronavirus. Parental reluctance seems to stem in part from the fact that the infection is known to be less risky for children.
“The risk of a child getting severe Covid is much, much, much lower – let’s be honest about it,” said Dr. Ofer Levy, director of the precision vaccine program at Boston Children’s Hospital and adviser to the FDA. .
Yet he said he had just treated a child with leukemia who had been hospitalized with Covid. “Some children get severe Covid, some end up in hospital,” he said, adding that more than 1,500 children under the age of 18 have died in the pandemic so far.
“I’m not into mandates, but I think families should be given the opportunity to protect their youngest,” Dr. Levy said.
In its trial, published in the New England Journal of Medicine, Moderna first tested different doses of its vaccine and chose a 50 microgram dose – half the adult dose – for children aged 6 to 11. The researchers then randomly assigned more than 4,000 children. receive two injections 28 days apart.
Three quarters of the children received the vaccine and the rest received placebo injections of salt water. About half of the children were from communities of color. To assess the potency of the vaccine, the researchers measured the antibodies produced after vaccination. (Pfizer’s vaccine trials relied on this same approach, called immunobridging.)
Children who received the vaccine produced slightly higher antibody levels than those seen in young adults, a promising sign. The trials were not large enough to assess the vaccine’s ability to prevent serious illness or death.
But based on a small number of Delta variant infections among the participants, the researchers estimated the vaccine was 88% effective against the infection.
“Immunobridging is basically an educated guess that we take – that the same level of immunity is going to be just as protective in a younger age group as it is in an older age group,” Dr. Permar said. “So it’s good to be able to track that effectively.”
The injections appeared to produce only minor side effects – including pain at the injection site, headaches and fatigue – and less often than in adults. About half of the children also had a fever for about a day.
This side effect can become a problem in children under age 5, because high fevers in very young children require invasive testing to rule out dangerous bacterial infections, Dr. Permar said.
The trial was not large enough to detect rarer side effects, such as heart problems that have been seen in other age groups. The Pfizer-BioNTech vaccine appears to cause fewer cases of so-called myocarditis in young children than in adolescents or young adults.
Moderna’s trial measured the potency of the vaccine against the Delta variant, and researchers are still evaluating its performance against Omicron. All vaccines were less effective, in all age groups, against the Omicron variant.
Independent scientists have reported that the Moderna vaccine elicits a strong immune response in children aged 7 to 11, and in adolescents, against the Omicron variant and other versions of the coronavirus.
But these antibodies seem to decline over time, as they do in adults. “Vaccine performance, in terms of vaccine efficacy, is unlikely to be as high in real-world data,” Dr. Levy said.
Dr Permar said she hopes the pandemic will bring about a change in the way vaccines are assessed in an emergency.
“We need to think of a different approach to include children and pregnant women in trials earlier,” she said. “And we have to do it now, because the next pandemic is going to happen before we want it to.”