When will the US have a Covid-19 vaccine for the youngest children?
(CNN) -- It's been more than a year since adults first got Covid-19 vaccines, but about 18 million children under 5 in the US are still waiting -- and will probably have to wait until the summer, despite some predictions that shots would be available in the first part of 2022.
While Moderna has shared some data on two doses of Covid-19 vaccine for younger children, Pfizer and BioNTech's data on three doses for younger children is not yet available.
The US Food and Drug Administration is weighing whether to consider emergency use authorization for both the Pfizer/BioNTech and Moderna Covid-19 vaccines for young children at the same time, rather than considering them separately, Dr. Anthony Fauci, chief medical adviser to President Biden, said Thursday.
"Two products that are similar but not identical, particularly with regard to the dose, and what the FDA wants to do is to get it so that we don't confuse people to say 'this is the dose. This is the dose regimen for children within that age group of 6 months to 5 years,' " Fauci, director of the National Institute of Allergy and Infectious Diseases, told CNN's Kasie Hunt.
The Pfizer vaccine was made to protect against the original strain of the coronavirus, and the initial series of two 3-milligram doses tested in kids under 5 wasn't powerful enough to keep them safe from the more infectious Omicron variant.
"It didn't meet the criteria for efficacy," Fauci said. "There was never a safety issue, but it didn't meet the criteria, which then had them go back and do a study with a third dose as a part of the primary regimen."
Pfizer CEO Albert Bourla said the goal is to have itsCovid-19 vaccine available for kids 4 and younger by summer.
"I hope, we will aim to make it in June," Bourla said on the "In the Bubble with Andy Slavitt" podcast, posted Monday. He said the FDA has been extremely collaborative and flexible during this testing and authorization process.
In a statement, the FDA said it couldn't comment on any particular company's Covid-19 vaccine EUA request but noted "that at this time, we do not have a complete EUA request in house to consider for children under 5 years of age."
"We continue to engage with companies to discuss their data, but we cannot adjudicate a decision on any vaccine without a complete EUA request, in order to allow us to do our thorough review. Any timeline on these actions is driven by when the data are provided to FDA and fully support a regulatory action," FDA spokesperson Abby Capobianco said.
Pfizer studying third doses
WhenPfizer and BioNTech were testing their vaccine for younger children with two doses, the FDA asked the companies to submit a request for emergency use authorization of that regimen; they said would continue to test a third dose as the two-dose regimen moved through the regulatory process.
In mid-February, the plan changed again. Dr. Peter Marks, director of the FDA's Center for Biologics Evaluation and Research, said the agency needed to see data on the third vaccine dose in these younger children in order to move forward with emergency use authorization.
Scientists working on clinical trials for the youngest children have the benefit of observing what happens with other age groups. After seeing breakthrough infections in 2021, especially with the rise of the highly contagious Omicron variant, researchers learned quickly that adults and adolescents needed additional doses of Covid-19 vaccine.
"When we started comparing not only against Delta, that was the previous one, but against Omicron, we realized the same thing as we realized in adults," Bourla said. "In adults, two doses, they provide very little protection against Delta. The third dose makes very strong. So we realized that this is the case also for pediatric, so we extended the trials to go to the third dose.
"We will provide you pretty soon data on the third dose, which we think will provide dramatically higher results," Bourla told Slavitt.
'Safety is of paramount importance'
Moderna has said its vaccine for younger children had a favorable safety profile, and for the Pfizer vaccine, Bourla said "so far, that the safety looks very, very good."
"My expectation is that we will have zero issues with safety. We're waiting to see the efficacy, and my expectation is that it will be very good," Bourla said.
"Safety is of paramount importance," Bourla said, which is why the company went with a lower dose of vaccine for young children than what's used in adults.
The biggest questions that remain for the Pfizer vaccines are exactly how protective the vaccines are, what the right vaccine schedule and dose is. The trials should answer these questions.
If the vaccine is authorized, little kids could get it on a different schedule than adults and adolescents. Rather than waiting four or five months before a third dose like older ages, the youngest age group could get a third shot as quickly as two months after the second.
Children are less likely than adults to be hospitalized or to die from Covid-19, but at least 463 children 4 and younger have died from the disease, according to the US Centers for Disease Control and Prevention.
"We need [the vaccines]," said Dr. Paul Offit, the director of the Vaccine Education Center and professor of pediatrics in the Division of Infectious Diseases at Children's Hospital of Philadelphia, and a member of the FDA's Vaccines and Related Biological Products Advisory Committee. "This virus is going to be with us until I'm dead. I can promise you that.
"We still vaccinate children against polio in this country, and we haven't had polio in this country for almost 50 years. Why? Because it still exists in this world. This virus is going to exist in the world and continue to do harm."
Offit said the world is going to need a population that's highly immune to the coronavirus for a "very long time."
"Every year, 3½ to 4 million children are born in this country who are unprotected. They are going to need to be protected for some time," he said. "And the sooner the better, the sooner you can do it safely."
Moderna moves ahead with two doses
Moderna has also been working on a vaccine for younger children. Dr. Paul Burton, the company's chief medical officer, said at the end of March that a vaccine for this age group is a "huge priority." The company plans to submit its application to the FDA and other regulators around the world "just as soon as we can."
Moderna said its Covid-19 vaccine performs as well in children as it does in adults.
Two 25-microgram doses provided a similar immune response for children 6 months through 5 years as two 100-microgram doses for adults 18 to 25, the company said, indicating that the benefit conferred to young adults is also conferred to young children.
The data showed it was safe and had "a robust neutralizing antibody response." The two doses are given to children 28 days apart.
Moderna said it was preparing to evaluate the potential of a booster shot for all children 6 months and older that would target the original strain of the virus as well as the Omicron variant.
Burton told Yahoo Finance last month that he wanted to be "realistic for the parents waiting."
"We're still talking a couple of months to the availability of the vaccine. This is not a couple of weeks," he said.
Steps parents can take now
While parents are waiting to vaccinate their little ones, there is something they can do to protect the children.
All adults who interact with the children should be vaccinated, the experts say, and ideally boosted. Adults are also advised to use masks around unvaccinated children, even as many mandates have fallen away.
Dr. Doran Fink, who oversees the FDA's clinical and toxicological review of investigational and US-licensed vaccines, told the US Centers for Disease Control and Prevention's Advisory Committee on Immunization Practices on Wednesday that he understood parents' concerns. He also promised that the FDA would work "diligently" to verify any data submitted.
"We know that many parents and caregivers and health care providers are anxious to have Covid vaccines available for this age group," Fink said. "I do want to reassure the committee and the public that we understand this concern, and we want to have available safe and effective vaccines for all age groups who will benefit from them."
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