When a US Food and Drug Administration advisory committee recommended Tuesday that the agency grant emergency use authorization for Pfizer-BioNTech’s Covid-19 for children between the ages of 5 and 11, it was based on data gathered during clinical trials conducted around the United States.
One of those clinical trials was conducted by Dr. Emanuel “Chip” Walter Jr., chief medical officer of the Duke Human Vaccine Institute and professor of pediatrics at the Duke School of Medicine in Durham, North Carolina. Walter held a briefing Wednesday on the Duke trial, sharing an insider’s perspective on the scientific process.
The clinical trial, which began in March, first investigated various reduced dosages of the Pfzier-BioNTech Covid-19 vaccine in children ages 5 to 11. The study determined that one-third of the adult dose, or 10 micrograms, produced an adequate immune response that was “best tolerated for children of that age, with the fewest side effects like fever, aches and chills and things like that,” Walter said.
That dosage was then administered in a larger trial of 4,500 children, of whom 3,000 were given the vaccine and 1,500 received a placebo.
“A study of 3,000 children getting the vaccine is actually a pretty good group if you’re looking for fairly common side effects,” Walter said.
Side effects of the vaccine in the children were carefully monitored, Walter said.
“Parents were given a diary to report symptoms on a daily basis for seven days after children received each dose of vaccine,” Walter said. “Usually the symptoms were pretty mild in most cases … and they resolved within a day or two.”
Manufacturers have taken precautions to eliminate mistakes in identifying adult and child vaccines, Walter said.
“The current vaccine has a purple cap in the vial. This one will have an orange cap on the vial. It will be labeled that it will be just for children. The adult dose should not be used for children,” he said.
He encouraged parents to prepare their children for an achy day after the shot.
“They may get a fever, they may feel a little achy, not feel as good the next day following vaccination, and that’s to be expected,” Walter said. “Those things can be managed pretty easily with ibuprofen.”
One safety concern has been the risk of myocarditis, an inflammation of the heart muscle and pericarditis, the inflammation around the heart, which has appeared occasionally in younger adults who received the vaccine.
Researchers do not know if younger children are at risk for myocarditis, but the study was careful to track any responses that might be warning signs.
There were no cases of myocarditis in the children’s trial, Walter stressed, despite a careful evaluation of every possible symptom.
“If a child complained of any pain, chest pain, or shortness of breath, families were immediately called and children were evaluated. So it was examined for quite closely in the trial, and there were no cases,” he said.
The risk for developing myocarditis is more commonly seen in men, particularly young men between the ages of 16 to 30, and typically after the administration of the second dose, Walter said. The rate of myocarditis in that particular group is “about 40 (cases) per million second doses of Covid-19 vaccine received,” he added.
“I think it’s really important to recognize that not all myocarditis is the same,” he added. “In fact, you can develop myocarditis after developing Covid-19 as a complication, and the myocarditis from Covid is usually quite severe and makes people quite ill and causes a prolonged hospitalization.”
However, the rare cases of myocarditis seen in younger men after vaccine is “generally fairly mild … and it’s usually very easily treated once it’s recognized.”
‘Robust’ immune response
In the study, children received doses of vaccine three weeks apart, just as with adults, Walter said. However, unlike larger adult trials, which track immunity and infections, the study only analyzed children’s immune response.
Levels of antibody protection in the younger children were then compared to levels seen in older children and adults up to age 30. Results showed children ages 5 to 11 produced similar levels of protection as the larger doses provided to older children and adults.
If a parent has an 11-year-old and is considering waiting until they turn 12 to be given the larger dose – don’t, Walter advised.
“I would not wait. At age 11, children will develop as good an antibody response or protection, protected level of neutralizing antibodies in the blood, from 10 micrograms of vaccine as they do from 30 micrograms. I’m confident they’ll have the same protection,” he said.
Obviously, a typical 5-year-old will be much smaller than a typical 11-year-old, which raises the question as to whether all children in that age range will be adequately protected.
“Yes, there are variations in size, but in terms of immune response, children between the ages of 5 and 11 should respond, no matter what their size is, with a good robust immune response to the vaccine,” Walter explained.
The children in the study will be followed for up to two years.
Covid-19 complications in younger kids
Many parents are weighing the costs and benefits of giving their younger child the Covid-19 vaccine, considering the widespread belief that most children are not in any serious danger from the virus.
“I think we’ve been lulled by this thought that the pandemic is worse for adults with comorbidities,” Walter said. “We need to realize that with this current Delta (variant) surge, children now account for about 25% of reported cases of Covid-19.
“When I last looked, there have been nearly 750 deaths from Covid-19 in children under the age of 18 – 160 deaths in this age group of between 5 and 11. That’s way more deaths than occur due to influenza in a typical year.”
In addition, Walter added, there are complications that children get from Covid-19.
“Children can have this condition where they get inflammation in multiple organs in their bodies – their heart, their lungs, kidneys, their GI tract, intestines. It’s called multisystem inflammatory syndrome of childhood (MIS-C) and it makes kids quite ill. There have been about 5,000 or more cases of (MIS-C) with 46 deaths.”
There are also potential long-term effects of Covid-19 in children, just as there are in adults, Walter added.
A very important reason why we should vaccinate children now, Walter added, is “to allow kids the freedom to be kids. Allow them to do all the things comfortably that kids need to do – go to school, do sports activities, after-school recreational activities and just do the normal things that kids want to do.
“My advice to parents is this is the best way to protect your child from serious illness and potentially death from Covid … get them vaccinated,” Walter said. “It’s the best tool we have. By all means I would recommend and suggest they get the vaccine.”
Emergency authorization safety protocols
Taking its advisory committee’s guidance into account, the FDA will decide next whether to authorize the vaccine. Then the US Centers for Disease Control and Prevention’s vaccine advisory committee will meet to consider whether it should be recommended for that age group. If CDC Director Dr. Rochelle Walensky signs off on that recommendation, younger children could be getting vaccinated next week.
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Some parents have expressed concern over the speed in which these trials in children have occurred, wondering if the safety protocols are different.
“There’s no difference in the safety standards,” Walter said, adding there is a sense of urgency due to the ongoing pandemic.
“You really have a public health emergency, so there is a need to get the data more quickly. Enrollment was more rapid, getting the data assembled was more rapid, getting the data reviewed is more rapid (because) it’s done on an ongoing basis with the FDA,” Walter said.
“So yes, there is a sense of rapidity, but it really is meeting all the same safety standards,” he added. “People can be reassured that the safety of this vaccine in children will be really comparable to that which is seen in adults.”