(CNN) Last week, the US Centers for Disease Control and Prevention issued guidance recommending the updated Covid-19 booster for children ages 5 to 11. Previously, the bivalent booster was recommended for children 12 and older, as well as for all adults. Now, the Pfizer/BioNTech booster is available for children 5 and older, and the Moderna booster can be given to children 6 and older.
What should parents consider when deciding whether to get the updated booster for their children? Are there circumstances that might prompt families to wait? Are there any downsides? What about children who just turned 5 — should they get the new booster? If a child has not been vaccinated yet, are they eligible for the updated booster?
To guide us through these questions, I spoke with CNN Medical Analyst Dr. Leana Wen, an emergency physician and professor of health policy and management at the George Washington University Milken Institute School of Public Health. She is also author of "Lifelines: A Doctor's Journey in the Fight for Public Health," and the mother of two young children.
CNN: Who is now eligible to receive the updated Covid-19 booster? Does it matter how many vaccines they've previously received?
Dr. Leana Wen: Essentially, everyone 5 and above can receive the new bivalent Covid-19 booster, as long as they have completed their primary vaccine series. It doesn't matter how many boosters they may have had. That means a child who received just the initial two doses of Pfizer or Moderna can get the booster, as can a child who already got one booster dose, as long as it's been at least two months since their last vaccine dose.
CNN: What should parents and caregivers consider before choosing the updated booster for their children?
Wen: There are two key questions to ask. First, is your child at high risk for severe illness due to Covid-19? The most important reason to get vaccinated is to reduce the chance of hospitalization and other severe outcomes. The initial two doses of the vaccine are very good at achieving this for most children. Some may still be at higher risk for worse outcomes, however — if a child has serious underlying medical conditions, for example, is on chemotherapy or is a transplant recipient. A booster dose would be advisable in these circumstances.
Second, is it very important for you to avoid Covid-19 infection in your children? Many families have decided that once their kids are vaccinated, if the risk of severe illness is very low, they do not prioritize eliminating Covid-19 infection.
On the other hand, others remain very vigilant and cautious. Perhaps they are concerned about the unknowns around long Covid. Perhaps they want to avoid their kids being sick, leading to missed school days and work days for caregivers. Or perhaps there is another household member to protect, such as an elderly grandparent or someone else with chronic underlying conditions. All of these are reasonable considerations for getting kids the booster sooner than later.
One thing I'll caution is that we don't know how long the booster will be effective in reducing symptomatic infection. Some studies have shown that the effectiveness of the primary vaccine against symptomatic infection may wane within a few months. That said, a lot can happen with Covid-19. We could see rising cases this fall and winter. There could be a new variant that becomes dominant. Many parents may want to get their kids optimal protection in case of another surge, and then decide again next year if another booster is needed.
CNN: Are there circumstances that might prompt families to wait to boost their kids?
Wen: If a child has just had Covid-19, I think it's advisable to wait at least three months, as the CDC recommends before boosting. Reinfection is unlikely in this time period, and it might be beneficial to allow the body time to develop its own immune response.
The same goes with a previous vaccine. The CDC says that children and adults can get the updated booster as long as it's been at least two months since their last vaccine shot.
I think these are both minimum intervals. Many experts, including me, believe that there is benefit to waiting longer — perhaps four to six months — after infection or last vaccination. That longer time period can allow the body to develop improved immunity before another boost, as some studies have suggested. However, I also understand and appreciate the CDC's need to have streamlined guidance, and it's reasonable to follow their guidelines as stated.
CNN: Is there any downside to giving kids the booster?
Wen: This is an important question to ask. The way that I'd answer is to clarify that every intervention — including vaccines — has upsides and potential downsides. Parents and families will weigh the upsides and downsides differently. The evidence is very clear that for the initial vaccines, the upsides far outweigh any potential risk. The evidence is less clear for boosters.
In the case of a child with serious underlying medical conditions, for example, there is a significant upside to getting the booster to prevent severe outcomes due to Covid-19. For other children, especially for younger children under 12, the initial vaccines are probably still very protective, and it's not yet clear what the added benefit of the booster is in reducing the risk of hospitalization.
There are some common side effects to Covid-19 vaccines. The vast majority are benign and self-resolving; symptoms like body aches, fatigue, fever, and soreness around the site of the booster jab usually go away in a couple of days. (There are very rare cases of myocarditis, an inflammation of the heart muscle most often seen in the adolescent male. These, too, tend to resolve on their own and do not cause long-term effects.) Broadly speaking, these should not be a major consideration for parents.
The CDC has recommended the booster, and I think it's reasonable for parents who wish to follow the guidance to do so. For those on the fence, having a frank conversation with your pediatrician about your family's specific circumstances can also guide you in your decision.
CNN: What about children who just turned 5 — should they get the new booster?
Wen: I have a son who recently turned 5, and received his primary series when he was 4. His last shot was in July. I am not planning to give him the booster yet. I'm waiting at least six months for the reasons mentioned above.
CNN: Can parents and caregivers choose to give their kids a dose of the original booster?
Wen: No. The US Food and Drug Administration has withdrawn its authorization for the original monovalent vaccine and replaced it with the updated bivalent booster. That means you can only receive the updated booster. That applies to children as well as adults.
CNN: If a child has not been vaccinated yet, are they eligible for the updated booster?
Wen: No. Children who have not yet been vaccinated can only receive the original vaccine for their primary series. Parents who wish for their kids to get the updated bivalent vaccine have to complete the primary series — two doses of Pfizer or Moderna — and then get the updated booster.
I want to emphasize the importance of the primary series. Numerous studies have found that the first two doses are highly protective against severe illness, including in kids. In one New England Journal of Medicine study, the first two doses of the Pfizer or Moderna vaccines reduced hospitalization among children by more than 80%. This should be a call to action for families who have not yet gotten their kids any Covid-19 vaccines to get them the initial vaccination.