Last week, the US Food and Drug Administration approved a bivalent Covid-19 booster for children 6 months to 5 years of age. The US Centers for Disease Control and Prevention has since recommended a booster, and now everyone 6 months and older can get the updated coronavirus vaccine, except for children who get three doses made by Pfizer/BioNTech.
Which young children are now eligible for boosters? But if children haven’t started or completed the full series – are they now getting the updated booster or the original monovalent vaccine? Can parents and guardians choose between the updated booster and the original shot? What are the possible side effects? What if children already had Covid-19? Which families should consider an updated booster now, and who can wait?
To help us answer these questions, I asked CNN medical analyst Dr. I spoke with Leana Wen, an emergency physician, public health expert, and professor of health policy and management at the Milken Institute School of Public Health at George Washington University. She is also the author of Lifelines: A Doctor’s Journey in a Public Health Challenge and is the mother of two young children, ages 2 and 5.
CNN: Let’s start with what’s changed in the recommendations: Which young children who received the Pfizer or Moderna vaccine are now eligible to receive a booster?
Dr. Leana Wen: There are two vaccines approved for young children: Moderna and Pfizer. For the youngest age group, the Moderna vaccine is designed to be a two-dose primary vaccine, while the Pfizer version is designed to be a three-dose primary vaccine. This means that young children are considered to have completed their main series if they have completed two doses of Moderna’s vaccine or three doses of Pfizer’s.
Note that there are now bivalent boosters for older children and adults. It combines the original (also called monovalent) vaccine with a vaccine that specifically targets the BA.4 and BA.5 Omicron subvariants. Because omicron subvariants account for nearly all new infections, the hope is that a bivalent enhancer will provide better, more targeted protection.
What federal health officials are now saying is that children 6 months to 5 years of age who received both doses of the original Moderna vaccine can receive the updated bivalent vaccine — if at least two months have passed since completing the initial vaccination series.
The instructions for children who received the Pfizer vaccine are slightly different, since the initial series already consists of three doses. Federal health officials said children 6 months to 4 years of age who have not yet completed three doses of the vaccine can receive a third dose of the bivalent vaccine. Suppose a child starts this series and receives one or two doses of the original Pfizer vaccine. The third dose can now be an updated booster.
CNN: And if kids haven’t started or completed the full series — are they getting the updated booster now or the original monovalent vaccine?
Ven: For Moderna and Pfizer, the answer is different. The initial series for Moderna is two doses, so the child should complete two initial shots with the original formula. Booster – the third dose – is a bivalent vaccine. The main series for Pfizer is three doses. The first two doses should still be the original formulation, but the third shot is now a bivalent vaccine.
CNN: What about young children who have completed three doses of the Pfizer vaccine — are they eligible for a fourth dose?
Ven: No. The FDA clearly says that children 6 months to 4 years of age who have completed their initial three-dose series with the original Pfizer vaccine are not eligible for a fourth shot of the bivalent booster. This is because the initial series of three vaccines is still expected to have strong protection against severe disease for Omicron. This recommendation will be reevaluated as new information becomes available.
CNN: Can parents and caregivers who haven’t completed Moderna’s primary series choose the bivalent vaccine as a second dose?
Ven: No. For Moderna, the FDA approval for the initial series in adults – two doses – is for the original monovalent vaccine. Similarly, adults do not have a choice about which vaccine to administer as a booster for Pfizer. Only the bivalent booster is available as a third shot, not the original monovalent, which is still available as one and two doses. This reflects the authorization for adults – the main series is a monovalent vaccine, the only booster for adults is an updated booster for Pfizer and Moderna.
CNN: What are the possible side effects of the updated booster?
Ven: Children who receive the updated booster are expected to have similar side effects to the original vaccine. These side effects are mild and short-lived, usually disappearing within the first 24 hours after vaccination. Adverse reactions may include pain and swelling at the injection site, fatigue, fainting, drowsiness, headache, muscle aches, and sometimes fever. Many children do not experience any side effects. In this young age group, the risk of serious side effects such as myocarditis (inflammation of the heart muscle) is expected to be extremely rare.
CNN: What if children already had Covid-19?
Ven: According to the CDC, people with Covid-19 can wait three months after recovering from the coronavirus to get another dose of the vaccine. They probably have a very good defense against infection during this period.
Multiple studies have shown that hybrid immunity—recovery from Covid-19 combined with a vaccine—provides very strong protection, perhaps more so than the vaccine and boosters alone. In my opinion, I believe that if a young child has received the initial series and already has Covid, they can expect to receive another booster dose. This is especially true if they have had Covid in the last year. To my knowledge, there are no studies showing an additional benefit of boosters for young children who have recently had a Covid-19 infection and received their primary vaccinations.
CNN: Which families should consider an upgraded amplifier now, and who should wait?
Ven: First, I think it’s important to note that the uptake of the initial series of Covid-19 vaccines among young children is very low. According to the CDC, less than 5% of children 5 and younger are fully vaccinated. This means we mean a very small kiddie pool that is new fit for upgraded boosters.
There is a group that I would definitely recommend buying a refurbished amp. This is the group of children who received the first one or two doses of the Pfizer vaccine. These guys need to complete their main series. The third dose in this series is now an updated bivalent booster. The families of these children have no reason to wait; they should complete the main series, and the third dose being updated to target Omicron is a bonus.
For children who receive two doses of the Moderna vaccine, I think the decision-making process is different and will depend on the families’ individual circumstances. Some families are very worried about the Covid-19 infection. Perhaps their child has an underlying medical condition, or they live with someone who is elderly, immunocompromised, or highly vulnerable to the severe effects of Covid-19. Perhaps the family is welcoming a newborn soon, and that baby will be especially vulnerable to coronavirus infection. I think it’s time for their youngster to get an updated booster since the Covid-19 cases are on the rise.
I also consider it appropriate to wait. My children (ages 2 and 5) received the Moderna vaccine over the summer. They are entitled to a boost, but I hold off because their defenses against critical illness remain strong. The booster will provide additional protection against symptomatic infection, but the effect is likely to be short-lived, according to the June study.
To be clear, I think it is very important for older adults and vulnerable individuals to receive an updated booster. I also think that people can choose an amplifier if they want, because there are individual reasons that are compelling for different households.
Parents and caregivers with questions should consult their pediatrician to determine the best course of action for their family’s specific situation. Finally, families whose children have not yet received the Covid-19 vaccine should consider getting started, especially if their child is not known to have Covid-19.