COVID-19 vaccine information

***For established patients only***

Are annual boosters recommended for my child?

IMPORTANT: this discussion only applies to children, the risks/benefits in adults may be quite different.

Summary and recommendations

We continue to recommend a primary vaccination series for all unvaccinated children, using the most up-to-date strain. We also recommend a booster with this new strain for children with any high-risk medical conditions. The evidence and consensus in support of these recommendations are high. While we would ideally like to see updated clinical trials with the new strain for the highest degree of confidence, it is most likely that the benefits will continue to far outweigh the risks in these situations.
We are also offering annual boosters to healthy, vaccinated children in alignment with the ACIP recommendations—in all likelihood the benefits, small as they may be at times do appear to outweigh the risks. However, due to the limited clinical trials, less scientific consensus, and possibly small observed benefit, we are not going so far as to say we feel strongly that all children who have already received the primary series must get a new booster every time. We feel that each family needs to take into account your situation and values, your child’s health, how well they tolerate shots, risk of exposure, and how disruptive a COVID illness would be to your family vs. how disruptive getting a shot is. See discussion below for more details.

Details and explanation

The answer differs whether we are talking about a primary series (for those unvaccinated with any COVID vaccine) or if we’re talking about booster doses for those who’ve already completed a primary series.

Primary series: Vaccination with a primary series is recommended for all children ages 6 months and up. All primary series will always be completed with the most current formulation. There is strong data and scientific consensus that primary vaccination reduces hospitalization, severe illness, and complications from COVID infection in children. This benefit is in addition to natural immunity, so the hybrid combination of vaccine immunity + natural immunity together are better than either alone. Even healthy children are at risk from complications due to COVID, and it is worth mitigating that risk with a vaccine that has demonstrated a very good safety profile, with far fewer risks than the illness itself. For infants less than 6 months old, those around them (parents, caregivers) should receive the vaccine to protect the infant until they are old enough to get their own vaccine.

Booster doses: Once vaccination with a primary series has been complete, the additional benefit conferred from booster doses is less certain. The remainder of this page will focus on this issue, though it will also include some safety information about the current vaccine relevant to those using it for their primary series.

Firstly, children at high risk of complication from COVID should get the booster dose (such as heart disease, obesity, diabetes, infants with prematurity, airway abnormality or significant genetic/developmental/neuromuscular conditions). Even if the additional benefit may be small, the vaccine has been well tolerated and any potential benefit in such high risk cases would be worth it.

For healthy, vaccinated children without any high-risk medical conditions, there is less consensus on how much difference an additional booster dose will make. To be clear, the Advisory Committee on Immunization Practices (ACIP) at the CDC recommends boosters each year to all children ages 6 months and up. However, there has not been complete consensus. The recommendation also differs from that of the World Health Organization and even the eminent vaccine advocate Paul Offit. Here are some of the reasons why there is not as much consensus about booster doses in healthy children:

Serious illness and hospitalization in children appear to already be at quite low levels after primary vaccination combined with wild type immunity from ongoing exposure. We have no conclusive evidence yet how much these outcomes could be improved with another booster, with some evidence suggesting it might not be. Immunity doesn’t need to be a perfect match to prevent severe outcomes, most children hospitalized from COVID were simply not vaccinated at all. Common sense would expect there would still be some reduction here, it just may not be a huge amount once that risk has already been reduced so substantially. We will need more data to confirm this however.
As for milder illnesses, to prevent an infection from occurring at all you need a much closer match. But COVID’s rapid mutation, huge diversity of strains, and lack of a predictable pattern make this challenging. Boost too soon and you get a weaker vaccine response, too late and you catch COVID while waiting. Only if you don’t catch COVID for 6+ months before your shot, then you DO catch COVID within 3-6 months after it, will you actually see optimal immunity, and such perfect timing is hard to accomplish.
That doesn’t make getting a booster pointless, it just makes the actual benefits a child might experience less than a booster’s theoretical effectiveness. For some kids the timing will work perfectly in their favor, even when the timing isn’t ideal there’s still probably some reduction in illness. Even a small benefit would outweighs the even smaller risks of the vaccine. So the question isn’t as much do the benefits outweigh the risks, but rather if that is by a large enough margin to exceed your threshold for coming in and giving your child a shot.

How many strains of COVID are there, and how well does the current vaccine protect against them? The example graph from the 2023-2024 season below shows the immense variation of strains in circulation, and how impressively quickly it changes over time. When the strain for the current booster was selected back in June, it was by far the most prevalent strain (purple, XBB.1.5 on the far left). But already by the time the vaccine was ready to administer, that strain was down to < 2%. That doesn’t mean it’s ineffective—it was shown to also induce antibodies for several other current strains, including EG.5. But it goes to show how broad a vaccine would need to be and how frequently it would need to be updated in order to have a dramatic impact on mild illness.

What safety and efficacy data is there for the current booster?

Direct safety and efficacy data on current strains will always be more limited than older vaccines, particularly when it comes to children. Most of the safety and efficacy is extrapolated from previous versions of the vaccine, for which there is ample data. After updating the strain, they will demonstrate the new vaccine can produce neutralizing antibodies against currently circulating strains, and confirm that on average at least in the small number tested, side effects were comparable to previous vaccines.

Typically, when there are minor changes to a proven vaccine, and it produces the antibodies desired, it’s unlikely that it will differ significantly from prior versions in terms of safety or effectiveness. There is a small risk that a different antigen could trigger an unwanted immune response, though this is rare. All vaccines undergo very close post-marketing surveillance to monitor for such a possibility just in case. But if we waited until a large trial with 100,000 children and adults could be observed over a long enough period, that strain would no longer be in circulation by the time you had the answer, so that really isn’t a feasible option.

In summary, it's usually a pretty safe bet that an updated vaccine will be as well tolerated and effective as previous versions, even without new clinical trials in children. That makes it fairly easy to recommend in settings where we know the benefits are substantial, as with the primary series. But it’s a bit more of a barrier to decisively recommending it where the benefits aren’t yet proven—continuing to boost healthy, vaccinated children—at least until the benefits of that approach are better established.

We hope this information is useful.

Last updated 9/17/2024