By Jen Christensen, CNN
(CNN) – One month after the U.S. Food and Drug Administration delayed important steps toward approving Covid-19 vaccines for children under 5, many parents are more eager for shots than ever before.
Dr. Daniel Leonard, a pediatric hospital physician working on the Pfizer / BioNTech vaccine trial for these children, said people are driving in from several states away to participate.
“We’re here in south central Nebraska, and while many may not think this would be the epicenter of scientific progress, the influx I’ve had with people from Colorado, Minnesota, Wisconsin, Iowa – some driving eight or nine hours each way overnight to participate in the study, “he said. “They are dedicated.”
About 18 million American children under the age of 5 are still not eligible for the protection of a Covid-19 vaccine. Children are less likely than adults to be hospitalized or die of Covid-19, but at least 400 children aged 4 and younger have died of Covid-19, according to US Centers for Disease Control and Prevention.
Experts say the wait for a vaccine may not be much longer.
Modern has said it expects to report experimental data for children ages 2 to 5 in March, and it may seek FDA cancellation, “if the data is supportive and subject to regulatory consultation.” Modern’s Covid-19 vaccine is currently only approved in the United States for adults.
Pfizer CEO Albert Bourla said Sunday he expects to get a vaccine for children from 6 months to 4 years “potentially in May, if that works.”
“And we want to be ready with production,” Bourla added on CBS ‘”Face the Nation.” Pfizer’s Covid-19 vaccine is already approved for individuals up to 5 years of age.
Johnson & Johnson, which makes the second Covid-19 vaccine approved in the United States, has a late-stage trial of a vaccine for 12- to 17-year-olds, but nothing for this younger group.
Waiting for more data
For a while, it had looked like the United States would have a vaccine for children under 5 years early in the first months of 2022.
Initially, the Pfizer and BioNTech vaccines for this age group were tested with only two doses, but the results were not what the researchers had hoped for, and the companies said they would test a third dose. However, at the request of the FDA, the companies submitted a request for an emergency use permit for two doses of the vaccine, saying they would continue to test a third dose as the two doses moved through the regulatory process.
in mid-February, the plan changed again. Dr. Peter Marks, director of the FDA’s Center for Biological Evaluation and Research, said the agency needed to see data from an ongoing trial of a third vaccine dose in these younger children to get ahead with emergency use permits. A February 15 meeting of the FDA’s advisory committee on vaccines and related biological products was delayed.
After all, families had to wait for data from the third dose.
“The immunogenicity analysis really showed that the immune response was really not where it should be,” said Dr. William Towner, who heads the Clinician Investigator Program for the Southern California Permanent Medical Group, on the vaccine trials. “I think the data is pretty strong that for children this will be a series of three doses.”
Two doses did not seem to do the trick, said Dr. James Versalovic, the pathologist-in-chief at Texas Children’s Hospital, where some Pfizer and Modern pediatric trials are underway. “The data were just not as robust as we had hoped in terms of immune response,” especially with children in the 2 to 4 range.
Researchers working on experiments with the youngest children have the benefit of observing what happens to other age groups. After seeing breakthrough infections in 2021, Versalovic said, researchers quickly learned that adults and adolescents need booster doses.
“By taking these lessons to ourselves, we just turned around at the end of December and just continued with a third dose and followed these kids during the trials,” he said. Children who have received a third dose must be monitored for at least two months before the data can be submitted to the FDA.
Investigators across the country confirmed that they are working as fast and diligently as they can to collect the data. Bourla said Sunday that the company should have data on their three-dose vaccine trials for this age group by April.
“The examinations need to be done correctly, and if it takes a little longer, it’s OK; let’s do it right,” said Dr. Sharon Nachman, a pediatric infectious disease specialist at Stony Brook University who worked on the Pfizer trials. “I think they need to be careful about assessing what the immune response is. How long does it last? And what did the third dose really mean?”
Another Pfizer researcher, Dr. Jennifer Nayak, a pediatric infectious disease specialist affiliated with Strong Memorial Hospital at the University of Rochester Medical Center, said it makes more sense to evaluate all data instead of some of them.
“Really, it’s about trying to get as much data as we can and being as careful as we can and coming up with the best recommendations,” Nayak said.
Dr. Jonathan Hand, an infectious disease specialist working on the Pfizer trial in New Orleans with Ochsner Medical Center, said all the careful work that goes into these trials should reassure parents when a vaccine is available.
“Data integrity and patient safety are so crucial to this process,” he said.
The good news, investigators say, is that they have not seen any security issues.
“The data is quite clear that there is good safety. It is not all published and it is not all public, but the vaccines are safe,” said Dr. Janet Englund, who works on the Pfizer trial at Seattle Children’s.
Comes with variants
The biggest questions that remain are exactly how protective the vaccines are, what the right vaccine schedule is and what the right dose is.
The results that will be released in the coming weeks and months should answer this question.
“We have always said that the main goal is to prevent hospitalization, but families want them to prevent infection in the household, especially if they have people in the household who are at risk as the elderly,” Englund said.
One challenge is that the vaccines are being tested in what researchers call a “second viral period.” The Covid-19 vaccines were developed from the original variant and tested during the Delta increase. Now, researchers are collecting data on the third shot, while the Omicron variant is the most dominant.
“Omicron somehow changed all efforts,” Towner said. “Omicron was highly mutated and apparently spread very rapidly.”
If approved, there is a chance that young children may receive a vaccine on a different schedule than what adults and adolescents receive. Instead of waiting four or five months before a third dose, as with older ages, they could get a third shot as soon as two months after the second shot.
“Children are not just small adults. They grow and develop through childhood,” Versalovic said. It affects how the vaccines work.
Another Pfizer researcher, Dr. Yvonne Maldonado, head of the Department of Infectious Diseases in the Department of Pediatrics at Stanford Medicine and a committee chair at the American Academy of Pediatrics, said they should soon know what they have. “I think we’re getting closer to some answers,” she said.
As with any vaccine trial, Dr. Claire Boogaard, a pediatric infectious disease specialist and medical director of the Covid-19 vaccine program at Children’s National in Washington, said it was important to remember that researchers are still learning about the disease while looking for ways to fight it. With variants can change very quickly.
“We want to encourage everyone to just be flexible, because that’s actually what science requires,” Boogaard said. “The reality is that there are many variables at stake.”
All scientists working on these experiments said they understand parents’ desire to protect their children. When the FDA postponed the meeting with its vaccine advisors, Marks said he understood the parents’ frustration.
Meanwhile, he urged parents to continue taking Covid-19 precautions: Make sure everyone around the child is vaccinated and rely on “masking procedures,” though it has become more difficult as the mask mandates fall.
As soon as the FDA gets the data needed to make a decision on vaccines for younger children, Marks said, it will proceed “very quickly.”
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