My Child Is Turning 12. Which COVID-19 Vaccine Should They Get?

If you’re the parent of a tween who’s still unvaccinated for COVID-19, you’re not alone. In the United States, only 16% of kids ages 5 to 11 are fully vaccinated and 25% are partially vaccinated, according to Jan. 3 data from the U.S. Centers for Disease Control and Prevention.

Now is the time to change that, experts say. As COVID-19 continues to spike across the country, low vaccination rates in this age group have resulted in record-high hospitalizations. COVID-19 vaccines ward off serious illness from the disease and reduce the odds of contracting Kawasaki disease (also known as Multisystem Inflammatory Syndrome in Children, or MIS-C), a potentially life-threatening condition. Among experts in childhood health, the consensus is that getting your eligible child vaccinated as quickly as possible is the best way to keep them healthy during the pandemic. The vaccine also very rarely causes serious side effects for children ages 5 to 11.

Since children ages 5-11 get a smaller dose of vaccine—10 mg instead of the 30 mg dose older kids and adults receive—parents often wonder whether they should delay their tween’s vaccination until they’re eligible to receive the larger dose. It’s a question Dr. Kristin Moffitt, an assistant professor of pediatrics at Harvard Medical School and a pediatric infectious diseases doctor and researcher at Boston Children’s Hospital, says she gets all the time from her patients’ parents.

Should your child wait to turn 12 to get a full dose or take the smaller dose now?

The short answer: “Get whatever vaccine your child is eligible for as soon as you can,” says Moffitt. “It doesn’t seem like there’s probably much immune benefit to waiting.”

Data from Phase 3 clinical trials for 5 to 11 year olds showed “excellent” immune responses, Moffitt says; this was still true when researchers broke down the participants into different age groups and compared their immune responses. Even 5 and 6 year olds had very similar immune responses to 10 and 11 year olds. Researchers also compared 10 and 11 year olds to 12 to 15 year olds who had received the larger dose, and found that their response was “incredibly similar,” she says.

The vaccine trials included kids in different stages of development, including before and after puberty. “We’re still seeing excellent immune responses across those ranges,” says Moffitt.

The “wildfire” spread of COVID-19 right now is another very good reason to get your child vaccinated as soon as possible, says Moffitt. Vaccines take time to confer protection, and the sooner children get vaccinated, the sooner they will be shielded from severe illness. They’ll even have a lower chance of contracting the virus in the first place.

If my child is big for their age, would they be better off with the larger dose?

The risks of leaving your child unvaccinated in order to turn 12 first are greater than the benefits, says Moffitt—even if it’s just for a short period of time or if your child is on the bigger side.

Because 10 and 11 years tend to vary a lot in terms of their development and size, a wide range of weights and heights was represented in the Phase 3 clinical trial, Moffitt explains. Given the strong immune response in the age group, “that suggests that what we have known about vaccines all along really held true: they are not weight dependent in terms of the expected response from a given dose,” she says. “The response really has to do more with how mature their immune system is.”

If my child gets an age-appropriate dose, will they be able to “upgrade” and receive a full booster dose when they turn 12?

The only authorized booster shots for kids are the full 30-mg dose from Pfizer-BioNTech, because boosters aren’t authorized for children under the age of 12 yet. While that may change in the future if smaller doses are approved, for now, the bigger shot is the only option. And since the COVID-19 vaccine for kids ages 5 to 11 was just authorized in October, you still have a little while to wait: the CDC also recommends waiting at least 5 months before getting a booster.

What are the drawbacks of waiting to give my child the vaccine?

Your child will be more likely to contract the virus and will be more vulnerable to severe illness from an infection. Even after they’re vaccinated, they won’t receive full protection from their vaccine course until two weeks after their shots.

Waiting to get your child vaccinated might also make the experience more unpleasant. Moffitt notes that kids ages 5 to 11 tend to have fewer and milder side effects from COVID-19 vaccines than 12-15 year olds, which may be attributable to the smaller dose they receive. Although vaccine side effects are rarely serious, Moffitt says that waiting to get your child vaccinated with the bigger dose might increase their odds of experiencing the mild effects associated with the vaccine—which range from sore arms to fevers—without offering significantly more protection.