COVID-19 vaccines for kids under 5: Pediatricians answer parents' questions

COVID-19 vaccinations for kids as young as 6 months old are now available after the Centers for Disease Control and Prevention (CDC) greenlit the Pfizer and Moderna COVID-19 vaccines.

CDC Director Rochelle Walensky issued a recommendation Saturday for how doctors, nurses and pharmacists should administer the shots.

Vaccines are on track to arrive as soon as Monday, according to a spokesperson with the Department of Health and Human Services (HHS).

At the start of the pandemic, scientists studied vaccines in adults first because they have a higher risk of dying of COVID-19. That means parents of children under the age of 5 have waited over two years for a COVID-19 vaccine for their kids.

Now that two vaccines are available, parents may have questions about everything from which vaccine and how many doses their child should receive to how safe and effective the vaccines are.

Here are answers from pediatricians across the country to common questions from parents.

1. Which vaccine should my child get, Pfizer or Moderna?

The short answer is that both the Pfizer and Moderna vaccines are safe and good options for kids under 5, pediatricians say.

"Basically, they're both very good choices," Dr. Yvonne Maldonado, professor of pediatrics at Stanford University and chair of the American Academy of Pediatrics Committee on Infectious Diseases, told ABC News. "It's always a great idea to have a choice for vaccines."

Among the factors that will come into play on vaccine choice include which vaccine is available locally, parents' preference and pediatricians' recommendations, according to Maldonado.

The main difference between the two is that Moderna's vaccine is delivered in two shots, taken 28 days apart, and Pfizer's vaccine requires three shots over the course of around three months.

Pfizer's data shows that fuller protection against COVID-19 does not kick in until the third shot, meaning a child who gets that vaccine will take longer to be protected against the virus.

Moderna says its vaccine is about 40 to 50% effective after two shots, and the company expects to roll out a booster, or third shot, in the coming months.

The Pfizer vaccine has already been available for those who are 5 and older but is now available for kids ages 6 months through 4 years.

Moderna's vaccine has previously been available only for people ages 18 and older. The latest vaccine authorization is for kids ages 6 months to 5 years.

2. Does it matter that Pfizer and Moderna's vaccines have different doses?

No, according to Dr. Vandana Madhavan, a pediatric infectious disease specialist at Mass General Hospital and professor at Harvard Medical School.

"What is most important is that both vaccines have the lowest doses given to the youngest children so that they are protected without increased side effects," she said. "The actual dose is less important than the level of protective antibody that a particular vaccines pushes the immune system to make."

The Pfizer vaccine is 3 micrograms -- one-tenth of the adult dose -- given in three doses.

The Moderna vaccine is 25 micrograms -- one-fourth of the adult dose -- given in two doses.

3. Will my child have side effects from the vaccine?

The side effects in children who get vaccinated against COVID-19 are typically mild, according to Madhavan.

"The most common side effect from the COVID-19 vaccine in all age groups is a sore arm at the site of an injection," said Madhavan. "Children might get a low-grade fever, generalized fatigue and crankiness but these side effects are less common and self-resolved, going away in a couple of days."

4. Why does my child need to be vaccinated against COVID-19 at such a young age?

While COVID-19 has had a more deadly impact on older adults, there have still been nearly 500 deaths in kids under 5 and over 30,000 hospitalizations in the U.S.

"One of the main issues is parents thinking that COVID-19 is a very mild disease, and the vaccines are very unsafe," said Dr. Diego R. Hijano, pediatric infectious disease specialist at St. Jude Children's Research Hospital. "And we cannot emphasize that the opposite is true."

Dr. Tanya Altmann, a California-based pediatrician and school physician, said getting a child vaccinated against COVID-19 can not only help prevent immediate illness but also protect them from longstanding complications from the virus.

"Kids under age 5 deserve and need protection just as older kids and adults against the potentially serious complications from COVID-19 infection," said Altmann. "The vaccine has reduced hospitalizations from COVID-19 in all other age groups and emerging data also shows a decrease in long COVID."

Madhavan stressed that it is important to get as many children vaccinated as possible amid summer travel and camps and a return to school in the fall.

"We can’t predict what the summer and fall will bring with respect to new variants and how transmissible, how serious these variants will be," said Madhavan. "We do know that thus far, vaccines are very effective at preventing serious disease from all variants."

5. How do experts know the vaccine is safe for young kids?

Both Pfizer and Moderna released data showing the vaccines proved safe in clinical trials for kids ages 6 months through 4 years, or 5 years for the Moderna shot.

Dr. Jay Portnoy, a professor of pediatrics at the University of Missouri-Kansas City School of Medicine and a member of the FDA advisory committee, called the vaccines "very safe to use."

“Our question today is, does the benefit outweigh the risks of this vaccine? And I think that the evidence is pretty clear," Portnoy said at Wednesday's meeting. "For preventing severe disease, hospitalization, emergency visits, this vaccine is very effective, very safe to use."

6. How do I get a vaccine for my child?

Parents should talk to their child's pediatrician about where and how to get a vaccine.

Pediatricians' offices, children's hospitals and family doctors' offices are all among the top sites for kids under 5 to get vaccinated.

"Remember, pediatricians get vaccines all the time. It's a large part of what they do," said Maldonado, adding that the American Academy of Pediatrics has already been working with the CDC and local health departments to coordinate the vaccine rollout for kids under 5. "They're used to rolling out new vaccines on a regular basis."

7. If my child had COVID, do they still need to get vaccinated?

Yes, pediatricians say.

"Individuals who have a combination of infection and vaccines have the best protection of all," said Hijano, describing a concept called hybrid immunity. "They are better than those who only got the vaccines and significantly better than those who only got infected."

According to Hijano, getting kids vaccinated, including those have already had COVID-19, will be especially important as the virus continues to change and new variants emerge.

Kids can get vaccinated as soon as they are out of isolation from COVID-19. They do not have to wait a certain amount of time, according to Hijano.

Priya Jaisinghani, M.D., is an endocrinologist at New York Presbyterian-Weill Cornell and a contributor to the ABC News Medical Unit.