COVID-19 Vaccine for 5-11 year olds: Kids vs. Adults

Children ages 5-11 can now get the Pfizer COVID-19 vaccine. Here is how the child vaccine differs from the adult vaccine.

Nov. 2, 2021 5   min read

After months of careful study, analysis, debate and review, the Pfizer-BioNTech COVID-19 vaccine has been given emergency use authorization (EUA) for children ages 5-11.

Pediatrician Steven Schulz, MD, and Pediatric Infectious Disease and Immunology specialist Michael Pichichero, MD, who has been involved in development and testing of more than a dozen pediatric and adult vaccines, are two physicians in the greater Rochester area who have a thorough understanding the vaccine and the process that led to its EUA approval – both in children and adults.

What was the approval process like?

The approval process for the COVID-19 vaccine in adults and children was quite similar.

Both began with multi-stage clinical trials that enrolled volunteers. After several months of collecting data and compiling it, researchers submitted the data to the FDA. A panel of experts reviewed the data compiled by the FDA and met to discuss it. After the panel voted to approve the vaccine for EUA, the FDA gave its approval, as well.

This was followed by a CDC panel of experts conducting a similar review, discussion, and voting process. CDC Director Dr. Rochelle Walensky made the final recommendation to endorse use of the vaccine for EUA in the 5-11 year old age group.

Discussion by the FDA and CDC expert review panels focused on:

  • The risk of severe COVID-19 infections among 5-11 year olds – specifically the serious multisystem inflammatory syndrome (MIS-C)
  • The ability of children in this age group to spread the COVID-19 virus weighed against the unknown risks
  • The possible risk of transient inflammation of the heart called myocarditis, noted among older children and young adults – especially males
  • Concerns that schools would mandate vaccinations if approval was granted.

“The immunity protection was 90.7 percent and side effects from the vaccine were virtually identical to older children and adults, as expected,” Dr. Pichichero said.

Ultimately, the FDA expert panel voted 17-0 with one abstention to approve the EUA.

“The approval of a COVID-19 vaccine for younger children has come later than approval for older children and adults because vaccine testing almost always begins with adults and proceeds down the age spectrum as a safety precaution,” Dr. Pichichero said. “Plus there are fewer research centers with experience in testing vaccines in younger children.”

Size and number of doses

Children in the 5-11 age group will not get the same amount of the Pfizer vaccine as an adult would receive.

Instead, a dose for a child would be 1/3 the amount of an adult dose. The scientists based this dosage on the average weight of a child in the age group and compared it to the average weight of an adult.

The 1/3 dose produced a protective immune response in the studied children and prevented symptomatic COVID-19 infection in 90.7 percent of enrolled 5-11 year olds.

Like adults and older children, 5-11 year olds will receive two doses of the Pfizer vaccine to be administered three weeks apart.

Side effects

Similar to adults and older children, children in the 5-11 age group experienced some side effects after getting the vaccine in the trials.

The list of side effects was virtually the same for both groups, including:

  • Low-grade fever (100.4° or lower)
  • Body aches
  • Chills
  • Nausea
  • Fatigue

If experienced, the side effects last 24-72 hours in most cases.

In rare cases among older children and young adults, mostly among males, transient, self-resolving inflammation of heart muscle called myocarditis has been observed.

“No child developed myocarditis during the test of the Pfizer vaccine in the 5-11 year old age group,” Dr. Pichichero said. “However, since fewer than 5,000 children were in this study and the myocarditis side effect occurs in 1 in 125,000, it was not possible to exclude the possibility of the rare side effect from the clinical trial data.”

Efficacy of the vaccine

Data from the clinical trials showed the Pfizer vaccine has a 90.7 percent efficacy rate for 5-11 year old children to prevent symptomatic COVID-19 infections, compared to a 96 percent for adults.

The variance between the rate for children and adults is not considered to be significant because of the difference in the number of participants in the clinical trials.

“Those percentages are virtually identical,” Dr. Pichichero said.

“Some other vaccines, such as the flu vaccine, are in the 60 to 80 percent range when it comes to efficacy. To have a vaccine with such a high rate of protection against a virus is exceptional,” Dr. Schulz said.

What comes next?

Pediatrics offices, urgent cares, pharmacies, schools, and community health clinics have begun receiving doses of the COVID-19 vaccine to administer to 5-11-year-old children.

Starting Monday, November 16, Rochester Regional Health will have the lower 5-11 year old doses of COVID-19 vaccine available at nearly all Pediatric and Family Medicine offices across Western New York and the Finger Lakes.

Patients can now contact their provider and schedule a vaccine appointment.

One of the benefits of vaccinating more children will be a reduction in the number of overall cases – which will help to reduce emergence of new virus variants like the Delta variant and reduce the number of COVID-19 tests being requested by schools and parents. The number of COVID tests being requested is something that is causing a significant strain on the healthcare system – specifically at pediatric offices and urgent cares.

“In the upstate New York region, pediatric offices and urgent cares are at their maximum in dealing with the need to do COVID testing – predominantly for 5-11 year olds,” Dr. Schulz said. “I don’t know that we can sustain this level of care of taking all these tests on these children seeking COVID tests for a sniffling nose and any child exposed to a child with a sniffling nose.”

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