How are Pfizer and Moderna vaccines for young children different?

How are Pfizer and Moderna vaccines for young children different?

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

“I think both are very effective with very large side effect profiles and I would not hesitate to give them to my children,” said Dr. Nina Alfieri, a pediatrician at Ann & Robert H. Lurie Children’s Hospital in Chicago. . “I think both are very 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 vaccine against Covid-19 is now licensed for children 6 months to 5 years of age. Pfizer’s is for children ages 6 months to 4 years.

The Pfizer vaccine was previously approved for children up to 5 years of age. Moderna’s vaccine for people ages 6 to 17 was recently approved by the U.S. Food and Drug Administration, and CDC vaccine advisers will vote this week on whether to recommend it.

Dose size and schedule

A child who gets the Modern vaccine will not have to go to the doctor or the pharmacy so often, and will get protection a little faster than the Pfizer vaccine.

The Modern series is completed with two doses of 25 micrograms administered one month apart. Children with a compromised immune system would have a third injection. The Modern photo for young children is a quarter of the size that adults get.

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With Pfizer, three shots are needed for the series to be complete. The company initially tested two doses, but test data showed that after the second dose, the vaccine did not elicit enough immune response. The three-dose vaccine released last week is one-tenth of the dose of Pfizer for adults.

With Pfizer, the first two shots are three weeks apart. The third can be given at least eight weeks after the second. In total, the child can take almost three months to complete the series.

Later, scientists may want children to receive booster vaccines from any of the companies.


Children were a little more likely to have a fever with the Modern vaccine; spent about a quarter of trial participants, compared to less than 10% with Pfizer. Most fevers were mild. Less than 1% of all test participants had a fever that reached 104 degrees.

“That was weird, but I think if we’re not honest with parents, when these things come out, that’s going to be worrisome,” said Dr. Grant Paulsen, principal investigator of the Pfizer and Modern Covid-19 vaccine. clinical trials for children ages 6 months to 11 years at Cincinnati Children’s.
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“Chances are most kids will be fine and have really minimal problems,” he said. “Most will have no major side effects.”

Moderna said other fever-causing illnesses were circulating during the trial, and this could have caused some of these fevers, as 10.6% of the children in the placebo group in the trial did not receive the vaccine. they reported fever.

Dr. Claudia Hoyen, a pediatric infectious disease specialist at UH Rainbow Babies Hospitals in Cleveland, said she understands why parents hate seeing their child develop a fever, but they should be reassured that the fever does not causes no permanent or long-term damage. problems in the long run and should be resolved quickly on its own or in response to over-the-counter medications such as Tylenol or Motrin.

“I think if you continue take that into account and realize that, yes, it’s scary, but it can be manageable. “ Hoyen said. “People should work with their pediatrician. I think a lot of kids with the first dose may or may not see a fever, but people should work with their pediatrician in case they do and have a good plan and that’s it. the best thing to do is to resolve it quickly. ”

General side effects

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

Children also have long Covid, and it can appear unexpectedly

Side effects of both more commonly included pain at the injection site and sometimes there was swelling or redness.

As for systemic symptoms or the whole body, the most common was fatigue or drowsiness. Some children had irritability or irritability, loss of appetite, headache, abdominal pain or discomfort, enlarged lymph nodes, mild diarrhea, or vomiting. But everyone improved quickly.

“It’s very similar to the side effects we’ve seen in older children or adults. About 24 hours of some kids, you know, they don’t feel so good, they feel tired, they don’t feel the same appetite. But thankfully, there have been no serious side effects of these vaccines, “Dr. Ashish Jha, White House Covid-19 response coordinator, told CBS on Monday.

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

Effectiveness of the vaccine

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

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

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

For the Pfizer vaccine, there were only 10 cases of Covid in the vaccine group and the placebo group in the trial, a figure too small to estimate the effectiveness of the vaccine. However, the first-line effectiveness data from the preliminary findings are “encouraging,” according to the company. And the FDA said the immune response to the vaccine between 6 and 23 months of age and 2 to 4 years was comparable to the immune response of older participants, but more research will be needed.

Conclusion: Get vaccinated

Get the vaccine that is available, experts said.

“I don’t think it’s clear that one is better than the other. They’re different,” Paulsen said. “It’s very much what parents prefer. Balancing these differences and honestly what’s available and what your pediatrician or the local hospital has.”

Doctors also suggest searching online or calling to find out what the local site has to offer. Not all locations will offer both outlets. Some vaccine clinics may also not offer vaccines for young children or may have restrictions on the ages they serve. CVS stores that have MinuteClinics, for example, will vaccinate this new age group, but only if the child is 18 months or older. may be helpful. The website provides information on clinics categorized by category.

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