• COVID-19 vaccines for kids as young as 6 month old could be available next week.
  • First, the CDC has to give a final signoff. 
  • Many experts are already expressing a preference for one brand, but both are good options. 

Little kids, toddlers, and babies as young as 6 months old will likely be lining up for COVID-19 vaccines in pharmacies, doctor’s offices, and vaccine clinics across the US in just a few more days.

The Food and Drug Administration gave its vote of confidence for shots from Moderna and Pfizer to start going into little arms on Friday. The move still requires a final signoff from the Centers for Disease Control and Prevention this weekend, but the White House is already planning for vaccinations to start “as early as the week of June 20.”

Because there are two different brands being offered, with different formulations, dose schedules, and side effects, parents are already weighing which shot is best for them and their children.

“Both are great options,” ER doctor Jeremy Faust wrote in his Inside Medicine newsletter, expressing confidence in both Pfizer and Moderna

However, Faust, along with public health expert Katelyn Jetelina and prominent parenting author Emily Oster have all decided that Moderna is the top pick for their own young kids. 

Their reasoning boils down to the fact that, according to early data, Moderna’s shot appears to pack a bigger immune punch, and it does the job faster. While short-term side effects are slightly worse with Moderna than with Pfizer, Moderna kids appear to gain protection against COVID in a matter of weeks, not months.

Faster protection with Moderna

Ilana Diener plays with her son, Hudson, 3, at home in Commack, N.Y. on Nov. 30, 2021, before an appointment for a Moderna COVID-19 vaccine trial.

Three year old Hudson (pictured with his mom) enrolled in Moderna’s pediatric COVID-19 vaccine trial for kids as young as 6 months old in 2021.
AP Photo/Emma Tobin

Moderna’s vaccine for babies and toddlers includes a bigger dose of mRNA than Pfizer’s, which may be part of the reason why FDA data suggests Moderna’s shot prompts faster protection with fewer shots.

“The three-dose Pfizer series takes nearly 90 days to go into effect,” Faust said. “Moderna’s two-dose series is considered effective by day 42. That means Moderna recipients get protection much sooner.”

Faust even created his own model chart, forecasting COVID-19 illnesses in little kids, based on insights gleaned from the clinical trials. His model shows Moderna kids achieving some protection against COVID-19 illnesses about a month and a half before Pfizer kids do. But keep in mind that these are estimates, based on the available data we have so far: 

graph showing moderna protection kicks in at one month, while pfizer kicks in at three

Inside Medicine

According to FDA data sets, little kids who received Moderna in the company’s clinical trials begin receiving some protection against COVID illnesses shortly after their second dose (administered at 30 days).

Kids under 5 who got Pfizer’s vaccine didn’t see much of a benefit kick in until they received their third dose, which means it took almost three months for them to achieve meaningful protection against symptomatic COVID. 

Based on the FDA breakdowns, it looks like toddlers over 2 years old gain some immune protection a little faster than babies do, both with Pfizer and with Moderna. But generally speaking, it’s about a month to a month and a half for Moderna, versus three months for Pfizer. 

“Parents should feel comfortable getting either one of these vaccines,” Dr. Peter Marks, who runs the FDA’s vaccine division, said on Friday during a call with reporters. 

“It may be that the Moderna vaccine brings an immune response slightly more rapidly,” he said. “On the other hand, the three dose Pfizer regimen may also bring a greater immune response after the third dose.”

Pfizer’s 80% efficacy appears better than Moderna’s — but Faust is skeptical about it

Pfizer said its three-shot vaccine was around 80% effective during trials. But this is a preliminary number, based on only 10 COVID cases observed over the course of 40 days. 

Moderna’s roughly 40% to 50% vaccine efficacy estimate for kids 6 months to 6 years old includes more kids, and a longer follow-up period of around 70 days. 

Faust speculated that Pfizer’s high effectiveness numbers might’ve been indicative of a “honeymoon phase” for the vaccine, where the three jabs initially provide outstanding protection against infection. While public health experts agree that 80% figure may fade, Faust is confident that protection against “serious outcomes” like hospitalization and death will “hold up over time.”

“Infections were starting to occur in a few Pfizer recipients just at the end of the assessment period,” he said. “It’s likely that with a few more weeks of data, Pfizer’s efficacy might have dropped some, leading to numbers closer to Moderna’s.”

Some parents might prefer Pfizer’s milder side effects

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

For toddlers and pre-schoolers, arm pain was far more common for Moderna-takers than for those who got Pfizer.

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

Bottom line: there isn’t a ‘wrong’ choice 

woman with a mask on signing about eating food to baby in a high chair

Amy McCoy signs to a baby about food at her Forever Young Daycare in Mountlake Terrace, Washington.
AP file photo/Elaine Thompson

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

“The correct answer here is: whatever vaccine your healthcare provider, pediatrician has, that’s what I would give my child,” Marks said.  

Vaccines help prevent long COVID, and while they aren’t flawless at stamping out infections, they still slow the spread of disease through communities by reducing the amount of time people are infectious, and by preventing some  disease, especially (and importantly) the severe kind. 

“It’s nice for parents of young children to have two options in the fight against COVID-19, instead of none,” Faust said.

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