How are Pfizer and Moderna vaccines for young children different?

Both use an mRNA platform and both are considered safe and well tolerated. Pediatricians CNN has spoken to across the country suggest that either is a good option.

“I think they are both highly effective with very large side effect profiles and I would not hesitate to give them to my children,” said Dr. Nina Alfieri, pediatrician at Ann & Robert H. Lurie Children’s Hospital in Chicago. “I think both are really good options.”

Both appear to create protective antibodies in young children as they do in young adults. There are only subtle differences and one may be more suitable for some children than the other.

Moderna’s Covid-19 vaccine is now licensed for children aged 6 months to 5 years. Pfizer’s is for children aged 6 months to 4 years.

Pfizer’s vaccine was previously licensed for children under the age of 5. Moderna’s vaccine for people ages 6-17 was recently cleared by the U.S. Food and Drug Administration, and the CDC’s vaccine consultants will vote this week on whether to recommend it.

Dose size and schedule

A child receiving the Moderna vaccine will not have to go to the doctor or pharmacy as often and will receive protection a little quicker than the Pfizer vaccine.

The Moderna series comes complete with two 25 microgram doses given one month apart. Children with compromised immune systems would have a third chance. The Moderna shot for young children is a quarter of the size that adults get.

With Pfizer, it takes three takes to complete the series. The company initially tried two doses, but the study data showed that after the second dose, the vaccine did not generate a sufficient immune response. The three-dose vaccine authorized last week is one-tenth the adult dose of Pfizer.

With Pfizer, the first two shots are given three weeks apart. The third can be given at least eight weeks after the second. In total, it can take nearly three months for the baby to have the full set.

Along the way, scientists may want children to receive boosters with the vaccine from both companies.


Children were slightly more prone to fever with the Moderna vaccine; it happened with about a quarter of the study participants, compared with less than 10% with Pfizer. Most of the fevers were mild. Less than 1% of all study participants had a fever that reached 104 degrees.

“It was rare, but I feel like we’re not being honest with the parents, when these things come up, it’s going to be troubling,” said Dr. Grant Paulsen, the site’s principal investigator for the Pfizer vaccine and Moderna Covid-19 clinical trials for. children from 6 months to 11 years at Cincinnati Children’s.
These children have lost their young parents to Covid-19.  Here's what they want other children, and adults, to knowThese children have lost their young parents to Covid-19.  Here's what they want other children, and adults, to know

“Chances are most kids will be fine and have very little problems,” she said. “Most won’t have any major side effects.”

Moderna said other diseases that cause fever were circulating during the study and that may have led to some of those fevers, as 10.6% of the children in the study’s placebo group who did not receive the vaccine reported fever. .

Dr. Claudia Hoyen, a pediatric infectious disease specialist at UH Rainbow Babies Hospitals in Cleveland, said she understands why parents hate to see their baby develop a fever, but they should be reassured that the fever does not cause any kind of permanent damage. or long-term problems and should resolve quickly on their own or in response to over-the-counter medications such as Tylenol or Motrin.

“I think if you continue remember that and realize that, yes, it’s scary, but it can be manageable “, Hoyen said. “People should work with their pediatrician. I think many children on the first dose may or may not even see a fever, but people should work with their pediatrician just in case they do and come up with a good plan and that will be the thing. best to do. It should resolve quickly. “

General side effects

The safety data from Moderna and Pfizer, audited by the FDA and the CDC, found that the potential side effects were mostly mild and short-lived.

Children also get sick with Covid and it can manifest itself in unexpected waysChildren also get sick with Covid and it can manifest itself in unexpected ways

Side effects for both most commonly included pain at the injection site and sometimes swelling or redness.

Regarding systemic or body-level symptoms, the most common were fatigue or sleepiness. Some children had irritability or fussiness, loss of appetite, headache, abdominal pain or discomfort, swollen lymph nodes, mild diarrhea, or vomiting. But they all got better quickly.

“It’s very similar to the side effects we’ve seen for older kids or adults. About 24 hours of some kids, you know, they don’t feel well, they feel tired, they don’t have the same appetite. But luckily, they don’t. There have been serious side effects of these vaccines, “Dr. Ashish Jha, the White House’s Covid-19 response coordinator, told CBS on Monday.

Scientists found no serious or rare side effects in the studies. They were watching closely for any signs that the children were developing problems with myocarditis, inflammation of the heart muscle, because there were a handful of cases among older children and adults. But myocarditis was not identified in the studies of young children.

Effectiveness of the vaccine

Both vaccines were tested when the Omicron variant was the dominant strain of the coronavirus. Studies show that, regardless of age or dose level, this particular variant has been more successful in circumventing the vaccine protection offered by both companies.

The Omicron variant was complicated for this age group in general. Without access to a vaccine, hospitalization rates among children 5 years of age and younger were five times higher during Omicron’s peak in winter, compared to when the Delta variant was the dominant strain last summer. according to a March report from the CDC.

Moderna is estimated to be 36.8% effective against symptomatic disease for children aged 2 to 5 years and protective against symptomatic disease by 50.6% for those aged 6 to 23 months.

For the Pfizer vaccine, there were only 10 cases of Covid in the vaccinated and placebo group in the study – too small a number to estimate the vaccine’s effectiveness. However, according to the company, the data on the topline effectiveness of the preliminary results are “encouraging”. And the FDA said the immune response to the vaccine from 6 to 23 months of age and 2 to 4 years of age was comparable to the immune response of older participants, but more research will be needed.

Bottom line: vaccinated

Get the vaccine available, experts said.

“I don’t think it’s clear that one is better than the other. They are different,” said Paulsen. “It’s a lot what parents prefer. Balance those differences and, honestly, what’s available and what their pediatrician has or what the local hospital has.”

Doctors also suggest searching online or calling to find out what the local site offers. Not all locations will offer both shots. Some vaccination clinics may not even offer vaccines for young children or may have restrictions on the age at which they are needed. CVS stores that have MinuteClinics, for example, vaccinate this new age group, but only if the baby is 18 months or older. can be helpful. The site provides some information on the clinics listed by category.