WASHINGTON. Over the past 10 months, as tens of millions of children and teens have received Pfizer-BioNTech’s vaccine, the companies’ main competitor, Moderna, has been sidelined, its vaccine restricted to adults.
But Moderna may now be back at a critical juncture in the nation’s vaccination campaign. The company is expected to send baseline data to federal officials this week on how well its coronavirus vaccine works on the nation’s smallest children.
About 18 million children under the age of 5 are the only Americans who are not yet allowed to be vaccinated. And while reaching out to older children has been slow, many parents still look forward to protecting their babies, toddlers and preschoolers.
Moderna goes toe-to-toe with Pfizer-BioNTech for the opportunity to vaccinate this group, hoping it has found what some scientists are calling a “Goldilocks” dose: strong enough to provide long-term protection, but not strong enough to cause widespread spread. worrisome side effects such as high fever.
Moderna opted for a two-dose/quarter-dose adult dose regimen for children under 6 years of age. Pfizer is expected to apply next month for a three-injection regimen for children under 5 years of age, with doses one-tenth that of adults. for people aged 12 and over.
Moderna is also expected to release clinical trial data for the next age group: children aged 6 to 11 years.
Dr. Yvonne Maldonado, Stanford professor of pediatric infectious diseases and lead researcher at Pfizer’s Stanford Pediatric Vaccine Trial Center, said new data from Moderna and BioNTech in the coming weeks will provide a critical analysis of the effectiveness of their pediatric vaccines. She said researchers are watching closely to ensure that stronger doses of Moderna “result in stronger immune responses” than Pfizer shots do in young children.
A series of new studies raising questions about how long Pfizer’s lower doses protect primary school children have sparked interest from federal scientists and vaccine experts in Moderna’s choice.
Dr. Ofer Levy, an expert in pediatrics at Harvard Medical School and a member of the Food and Drug Administration’s Independent Vaccine Advisory Committee, said he believes Pfizer may have chosen a too low dose for children ages 5 to 11. years for obvious reasons. priority for maximum safety.”
To date, Pfizer has been the only player in vaccinating young Americans, having received approval to vaccinate children aged 12 to 15 last May, and in October to vaccinate children aged 5 to 11. Its adult permit also covers 16- and 17-year-olds.
Moderna requested permission to vaccinate teenagers in June last year, but the FDA shelved the request due to concerns about the risk of myocarditis, a condition associated with inflammation of the heart that has been associated with both Moderna and Pfizer shots.
More than 22 million people under the age of 18 in the United States are now fully vaccinated with the Pfizer vaccine, but uptake is stabilizing. For example, only about one in four children between the ages of 5 and 11 are fully vaccinated, although this group has been offered vaccinations for more than four months.
But there is still a need to protect the youngest children as more countries unmask, more parents return to work and the summer travel season approaches.
Compared to adults, “there is no doubt that children benefit less from an effective vaccine because fewer people actually get sick,” said Dr. Eric Rubin, an infectious disease expert at the Harvard School of Public Health. T. H. Chana and a member of the FDA Advisory Group.
“But it will benefit some people,” he said. “It will save a few lives. Since the start of the pandemic, 336 U.S. children under the age of 5 have died from Covid, according to the Centers for Disease Control and Prevention.
Hopes that the youngest children will soon be covered skyrocketed last month after regulators required Pfizer-BioNTech to submit preliminary three-dose trial results. The FDA wanted to start a two-dose campaign while waiting for final results on three.
But those efforts collapsed when new data from Pfizer covering most of the Omicron surge conclusively showed that two doses failed to adequately protect against symptomatic infection.
Updated
March 14, 2022 2:34 AM ET
Now, more detailed test results from Pfizer and Moderna are coming out around the same time. And while neither company knows yet whether their vaccines will be effective enough for the youngest age group, both say their research shows they are safe.
“We haven’t seen anything adverse right now, so we’re confident about the safety profile,” Dr. Paul Burton, Moderna’s chief medical officer, said in an interview.
Amy Rose, a spokeswoman for Pfizer, said that after careful research, Pfizer-BioNTech has chosen the “safest and most tolerated dose” for young children. The companies said they hope the three-injection regimen will provide strong protection for children under 5 years of age. Pfizer is testing a dose of 10 mcg for children aged 5 to 11, i.e. dosing; and 3 mcg for children under 5 years of age.
Moderna offers significantly higher doses than Pfizer for all three age groups of children: 100 mcg, full adult dose, for children ages 12 to 17; 50 micrograms for children 6 to 11 years of age and 25 micrograms for children under 6 years of age. It is believed that regulators can simultaneously consider firm data for all three age groups.
“We really support these doses,” Dr. Burton said. While federal officials say the effectiveness of Pfizer and Moderna vaccines declines over time, some adult studies have shown that Moderna’s protection lasts longer. “I think it’s all about the dose,” said Dr. Burton.
He said initial results showed that a 50 mcg dose of Moderna caused a “sustained immune response” in children aged 6 to 11 years. Although the total number of infections was small, the researchers hope the trial will help find out how well the vaccine prevents the disease, not just how. high increases the level of antibodies.
Dr. Philip Krause, who recently stepped down as senior vaccine regulator at the FDA, said the agency spent a lot of time last year worrying about the safety of the Moderna vaccine for those under 18, with some studies showing a higher risk of myocarditis from the vaccine. companies. than from Pfizer.
“The question always arises: what dose elicits an immune response that we think might be protective?” he said. “You can’t really do a test to determine the frequency of myocarditis because it’s rare, but you can ask, ‘What are we sacrificing in the immune response by lowering the dose, and do we think it’s important?’
Partly because of concerns about myocarditis, the CDC recently recommended that some people aged 12 and older, especially boys and men aged 12 to 39, wait eight weeks between their first and second Pfizer or Moderna shots. Studies have shown that teenage boys and young men are most at risk of developing side effects.
Dr. Burton said overall the study was encouraging, including recent UK data showing that myocarditis was very rare and generally mild in both Pfizer and Moderna recipients.
But Dr. Walid F. Gellad, a drug safety expert at the University of Pittsburgh, said it remains unclear whether a higher dosage of Moderna might increase the risk of myocarditis in young children. The company’s pediatric studies are likely too small to determine the risk of a side effect, he and other experts said.
Moderna’s new push also comes after several studies have raised questions about the protection that two doses of the Pfizer-BioNTech vaccine provide to children 5 to 11 years old. Researchers at the New York State Department of Health recently found that protection against infection was significantly reduced after two doses within a few weeks.
CDC researchers separately found that during the Omicron wave, the efficacy of two doses of the Pfizer vaccine against mild forms of the disease in children aged 5 to 11 years was significantly reduced.
The studies have sparked a debate among vaccine experts about whether a stronger dose would be better or if these kids need third doses. Booster shots are now legal for everyone 12 and over. Pfizer is expecting results from a three-dose trial for young children next month.
Dr. Gellad said that perhaps the dose of Pfizer for children aged 5 to 11 years was too weak, but scientists cannot be sure yet. He said he expects regulators to be especially careful when considering higher doses for young children, given the relatively low risk of them contracting Covid now and becoming seriously ill.
Among all the questions, one thing is clear: disputes about which vaccine is best for young children may prevent its use.
Alison M. Battenheim, a behavioral health expert at the University of Pennsylvania, said those who considered getting vaccinated took comfort in confidence. Otherwise, “it’ll just pave the way for you to say, ‘I’ll refrain,'” she said. “Many people are dissatisfied with the development of science.”