What Parents Need to Know About Mixing COVID-19 Booster Shots for Children

COVID-19 vaccines are now widely available for everyone ages 6 months and older. Boosters are recommended for everyone ages 5 and up (except for children who received Moderna for their primary series) 5 months after completing their primary series with the Pfizer or Moderna vaccine and 2 months after the Johnson and Johnson (J&J) shot.

Now that so many different vaccines are available, many parents wonder which type of booster their child should get and when they should get their shot. The science and our understanding of COVID-19 are constantly evolving, which can make it hard to keep up. Parents are especially eager to understand what to do for their kids who are old enough to be vaccinated and receive boosters and/or for kids who are immunocompromised.

All vaccines available in the United States—Pfizer, Moderna, and Johnson & Johnson—went through rigorous testing before being provided to the public, and all have proven effective at preventing severe cases of COVID-19. Though all the COVID-19 vaccines and boosters are not fully approved for children of all ages, there is plenty for parents to know, including whether or not it's safe and recommended to mix and match vaccines and boosters.

Experts share their insight on what parents should understand about mixing and matching the COVID-19 vaccine and boosters in the younger set.

Guidelines for Mixing COVID-19 Vaccines and Boosters

In September 2022, the booster dose of Pfizer's COVID-19 vaccine was approved by the FDA. At that time, there wasn't concrete evidence to support whether or not people who initially received the Moderna or Johnson & Johnson vaccine should get the Pfizer booster. However, in October 2022, the FDA approved both Moderna and J&J boosters, making the booster process simpler, while also creating more choices.

In the FDA's October approval of the Moderna and J&J booster doses, the organization also noted that combining vaccine brands had been studied and approved. This includes "the use of each of the available COVID-19 vaccines as a heterologous (or 'mix and match') booster dose in eligible individuals following completion of primary vaccination with a different available COVID-19 vaccine."

The Pfizer and Moderna boosters are recommended to be administered 5 months after the initial vaccine. The Johnson & Johnson booster is recommended to be administered two months after the initial vaccine, however, at this time, the CDC recommends using the Pfizer or Moderna vaccine in place of the J&J vaccine in all but limited cases. Plus, the J&J vaccine is only authorized for use in adults, so kids cannot get it.

Can Children and Teens Mix and Match COVID-19 Vaccines and Boosters?

Boosters are now recommended for children 5 and up who were originally vaccinated with the Pfizer primary series. Children who get the Moderna series do not need booster shots at this time.

While adults can get mix and match their COVID-19 vaccines and boosters, eligible children are generally advised to stick with the Pfizer shot for their booster. This includes children who are immunocompromised or otherwise at greater risk for severe illness, such as those with cancer, diabetes, or Down syndrome. However, you can discuss with your child's pediatrician which booster shot is best for your child.

Pennsylvania-based pediatrician Jarret Patton, MD, FAAP, urges parents to err on the side of caution when it comes to mixing and matching the vaccine and booster doses. "For children who have been vaccinated, ideally, they should get the same brand as originally given in most cases," says Dr. Patton. "However, emerging guidance and research is now informing us that it is OK to mix brands of vaccines if necessary." 

As of now, there is no data on how mixing and matching vaccines affects children, says Christina Johns, MD, a pediatrician and senior medical advisor at PM Pediatrics. To that end, Dr. Johns agrees with Dr. Patton in being hesitant about children and teens mixing vaccine brands, especially this early in the research. "Parents should wait for guidance on mixing vaccine brands for their children," she says.

Both pediatricians advised parents to speak with their primary health care provider if they want to discuss vaccines and boosters for their children. This is especially important for children who are at a higher risk of contracting and getting sicker from the virus, like those who are immunocompromised.

Though there is less data on boosters for children and teens, your healthcare provider can advise you on a personalized plan for your child. Dr. Patton added that he advises parents to get vaccinated to further protect their children from getting sick.

While mixing and matching vaccine and booster doses has newly been approved by the FDA, it has not yet been recommended for children. As new research is done, doctors and scientists will be able to make more clear recommendations for families.