COVID

What to know about the coronavirus vaccine for children younger than 5

"We have waited a long time for this moment."

A 5-year-old boy receives his first dose of a coronavirus vaccine at Texas Children's Hospital in Houston on Nov. 3, 2021. Meridith Kohut/The New York Times


Children as young as 6 months old are now eligible to receive the coronavirus vaccine after the Centers for Disease Control and Prevention signed off on the shots for an additional 19 million children across the United States.

The CDC on Saturday unanimously recommended the Pfizer-BioNTech vaccine for children ages 6 months through 4 years as well as the Moderna vaccine for children ages 6 months through 5 years. The move came a day after the Food and Drug Administration amended both vaccine makers’ emergency-use authorizations to include the youngest age group.

“Together, with science leading the charge, we have taken another important step forward in our nation’s fight against COVID-19,” CDC Director Rochelle Walensky said in a statement after her endorsement. “We know millions of parents and caregivers are eager to get their young children vaccinated, and with today’s decision, they can.”

Advertisement:

Here are some things we know about the vaccine for young children.

When will the vaccine be available for children younger than 5?

The Pfizer-BioNTech and Moderna vaccine series should be available for children as young as 6 months old starting Tuesday, June 21.

Biden administration officials said that when these vaccines are available, they plan to make them as accessible as possible. Parents will be able to get their youngest children vaccinated at their pediatricians’ offices, as well as at pop-up clinics at children’s museums, libraries and child-care sites.

“We have waited a long time for this moment,” White House coronavirus response coordinator Ashish Jha said at a briefing Thursday. “We are on the cusp of having safe, highly effective vaccines for kids under 5.”

Will it be the same vaccine given to older children?

No, children in the youngest age group will be administered a smaller dose.

For the Pfizer vaccine series, children ages 6 months through 4 years will receive three 3-microgram doses, which is one-tenth of the adult dose. The first two doses will be administered three weeks apart, and the third dose will be given at least eight weeks after the second dose.

For the Moderna vaccine series, children ages 6 months through 5 years will get two 25-microgram doses — or one-quarter of the dose given to adults — four weeks apart.

What about the other vaccine?

Asked about a pediatric vaccine, Johnson & Johnson said in an email earlier this year that trials are underway for adolescents ages 12 to 17 but that the vaccine “is not currently authorized for use in children.”

Advertisement:

Do children younger than 5 need to be vaccinated against the coronavirus?

Some parents have asked whether younger children need the vaccine, particularly given that children tend to have less-severe illness than adults. But Paul Offit, the director of the Vaccine Education Center at Children’s Hospital of Philadelphia, said children still can “suffer and be hospitalized and die from this virus.”

Since the start of the pandemic, more than 13.5 million children in the United States have tested positive for the coronavirus, resulting in about 40,000 hospitalizations and more than 1,000 deaths, according to the most recent data from the American Academy of Pediatrics.

In addition, children are at risk of significant complications. More than 8,500 children have suffered a rare but serious condition called multisystem inflammatory syndrome (MIS-C), which is associated with COVID-19 and can cause inflammation of the heart, lungs, kidneys, brain, eyes and other organs, according to the CDC.

Should I be concerned about serious adverse reactions?

Although there is no real-world data on serious adverse reactions for children younger than 5, in general, such events are rare.

Anaphylaxis — a severe allergic reaction that can cause difficulty breathing, among other things — can occur after any vaccination, including the coronavirus vaccine. As of June 16, 80 reports of anaphylaxis after the Pfizer-BioNTech vaccine were reported to the Vaccine Adverse Event Reporting System (VAERS) for eligible children ages 5 to 17, but those cases have not been confirmed, the CDC said.

Advertisement:

Thrombosis with thrombocytopenia syndrome (TTS), which causes blood clots, is another known adverse reaction that is more often seen after the Johnson & Johnson vaccine. But it is exceedingly rare — even more so in the case of the mRNA vaccines. And the CDC said that there have been no reports of TTS in the VAERS among children of any age.

What about myocarditis?

There have been very rare instances of heart muscle inflammation in vaccinated adolescents and young adults. Although it has been reported after vaccination, experts say the coronavirus-caused COVID-19 itself is more likely to cause myocarditis than the vaccine, especially in children who develop MIS-C because of the disease.

More than 250 million Americans have received at least one vaccine dose, including more than 36% of people ages 5 to 11, 69% of people ages 12 to 17 and 78% of people ages 18 to 24, according to the CDC.

As of June 9, more than 1,000 preliminary reports of myocarditis or pericarditis (inflammation of the outer lining of the heart) were reported to the VAERS among people younger than 18 in the United States who received a coronavirus vaccination. About 650 of those cases have been confirmed, the CDC said.

Myocarditis, which can have many causes, is generally not as common among younger children.

“There’s every reason to be confident that it wouldn’t be a problem in the less-than-5-year-olds who are getting an even smaller dose than the 5-to-11-year-olds,” Offit said.

And in the low number of cases reported among children, experts say the vast majority have been mild and patients have recovered quickly.

Advertisement:

In general, Offit said parents should vaccinate their children against the coronavirus for the same reason they vaccinate them against other diseases — to protect them not only as children but also as they grow older, and to protect those around them.

“Knowing that children can suffer from this, knowing that children grow up and that they’re going to be susceptible to this virus,” he said, “we will need a high percentage of population immunity.”

What should I do while waiting for the vaccine?

In the meantime, make sure your child is up to date on all routine vaccinations, experts said.

Sean O’Leary, vice chair of the Committee on Infectious Diseases for the American Academy of Pediatrics, said although COVID-19 is understandably making parents nervous, “a lot of the diseases that we vaccinate kids for, like measles, are more severe in kids than COVID — and we have seen a global dip in those vaccines, and we are very concerned about potential outbreaks of those diseases.”

O’Leary said that while parents and guardians are waiting for a vaccine for children younger than 5, they should make sure those children have been vaccinated against these other diseases, including influenza.

“Those are things we can prevent,” he said.

The Washington Post’s Carolyn Y. Johnson, Laurie McGinley and Lena H. Sun contributed to this report.

Conversation

This discussion has ended. Please join elsewhere on Boston.com