Pfizer vs. Moderna for vaccinating children under 5: Which is better?

  • COVID-19 vaccines for 6-month-old children may be available next week.
  • First, the CDC must give final approval.
  • Many experts already express a preference for one brand, but both are good options.

Young children, young children and babies up to 6 months of age are likely to line up for COVID-19 vaccines in pharmacies, doctors’ offices and vaccine clinics in the United States in just a few days.

The Food and Drug Administration has given its vote of confidence to the photos of Moderna and Pfizer to go into small hands on Friday. The move still requires final approval from the Centers for Disease Control and Prevention this weekend, but the White House is already planning vaccinations to begin “as early as the week of June 20.”

As two different brands are available, with different formulations, dosing regimens and side effects, parents are already deciding which injection is best for them and their children.

“Both are great opportunities,” wrote emergency physician Jeremy Faust in his Inside Medicine newsletter, expressing confidence in both Pfizer and Moderna.

However, Faust, along with public health expert Caitlin Jetelina and renowned parent author Emily Oster, have decided that Moderna is the best choice for their own young children.

Their reasoning boils down to the fact that, according to early data, Moderna’s staff seems to have greater immunity and do the job faster. While the short-term side effects are slightly worse with Moderna than with Pfizer, Moderna’s children appear to receive protection against COVID for weeks, not months.

Faster protection with Moderna

Ilana Diner played with her son Hudson, 3 years old, at home in Comac, New York on November 30, 2021, before a meeting was scheduled to test the Moderna COVID-19 vaccine.

The three-year-old Hudson (pictured with his mother) enrolled in a pediatric trial of Moderna’s COVID-19 vaccine for 6-month-old children in 2021.

AP Photo / Emma Tobin


Moderna’s infant vaccine includes a higher dose of mRNA than Pfizer’s, which may be part of the reason why FDA data suggest that Moderna’s vaccine causes faster protection with fewer injections.

“The Pfizer three-dose series takes almost 90 days to take effect,” Faust said. “A series of two doses of Moderna is considered effective on day 42. This means that Moderna recipients receive protection much earlier.”

Faust even created his own model diagram predicting COVID-19 disease in young children based on insights from clinical trials. His model shows Moderna’s children achieving some protection against COVID-19 about a month and a half before Pfizer’s children. But keep in mind that these are estimates based on the available data so far:

a graph showing moderna protection that starts at one month, while pfizer starts at three


Internal medicine



According to FDA datasets, young children who received Moderna in the company’s clinical trials began receiving some protection against COVID disease shortly after the second dose (given every 30 days).

Children under 5 years of age who received the Pfizer vaccine did not see much benefit until they received their third dose, which means that it took them almost three months to achieve significant protection against symptomatic COVID.

Based on FDA breakdowns, it appears that young children over the age of 2 gain some immune protection a little faster than babies with both Pfizer and Moderna. But generally speaking, it’s about a month to a month and a half for Moderna, compared to three months for Pfizer.

“Parents should feel comfortable receiving one of these vaccines,” said Dr. Peter Marx, head of the FDA’s vaccines department, during a conversation with reporters on Friday.

“Moderna may be triggering an immune response a little faster,” he said. “On the other hand, Pfizer’s three-dose regimen may also lead to a greater immune response after the third dose.”

80% of Pfizer’s efficiency looks better than Moderna’s – but Faust is skeptical

Pfizer said its three-injection vaccine was about 80% effective during the trials. But this is a preliminary figure based on only 10 cases of COVID observed over 40 days.

Moderna’s estimate of approximately 40% to 50% efficacy of the vaccine for children 6 months to 6 years of age includes more children and a longer follow-up period of approximately 70 days.

Faust suggested that Pfizer’s high efficacy figures could be indicative of a “honeymoon phase” for the vaccine, where the three killings initially provided exceptional protection against infection. While public health experts agree that the 80% figure may fade, Faust is convinced that protection against “serious results” such as hospitalization and death “will last” over time.

“Infections began to appear in several Pfizer recipients just “At the end of the evaluation period,” he said. “It is likely that with a few more weeks of data, Pfizer’s performance may have fallen slightly, leading to numbers closer to those of Moderna.”

Some parents may prefer the milder side effects of Pfizer

Because Pfizer’s vaccine is a much smaller, less potent dose of mRNA than Moderna’s, it appears to come with easier side effects in the days after vaccination. The main things for babies are irritability and drowsiness.

For young children and preschoolers, arm pain is much more common for people taking Moderna than for those receiving Pfizer.

“Pfizer may also be particularly attractive to parents of children who have already had COVID,” Faust said, as those children may already have some immune protection.

In the end: there is no “wrong” choice

woman with a signature mask to eat baby food on a high chair

Amy McCoy signs for baby food at her Forever Kindergarten in Mountlake Terrace, Washington.

Photo of AP file / Elaine Thompson


Parents should be comforted to know that whatever vaccine they choose for their children is good.

“The right answer here is: whatever vaccine your healthcare provider, pediatrician, has, I would give it to my child,” Marx said.

Vaccines help prevent long-term COVID and, while not perfect in eliminating infections, they do slow down the spread of the disease in communities by reducing the time people are infected and by preventing certain diseases, especially (and importantly) ) heavy mil.

“It’s good for parents of young children to have two options in the fight against COVID-19 instead of one,” Faust said.

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