Young Children Could Soon Be Eligible for the COVID Vaccine. Here’s What to Know

February 2, 2022 By Andrew Ramspacher, fpa5up@virginia.edu Andrew Ramspacher, fpa5up@virginia.edu

Soon, Americans of all ages could be eligible to receive the COVID-19 vaccine.

The University of Virginia’s Dr. William Petri chatted with UVA Today earlier this week as Pfizer asked the Food and Drug Administration to authorize its vaccine for children under 5. Parents could be signing their youngest kids up for shots as early as March, and Petri, vice chair for research in the Department of Medicine, is here to answer several of their potential questions.

Q. In December, progress toward authorization of the vaccine for this age group seemed to hit a snag as clinical trials showed that low doses of the vaccine generated protection in children up to 2 years old, but failed to do so in kids aged 2 to 5. What’s changed since then? 

A. You are correct that back on Dec. 17, Pfizer announced in a press release that they were going to change the clinical trial of the Pfizer-BioNTech COVID-19 vaccine in children aged 6 months to 5 years. The clinical trial enrolled 4,500 children in the U.S., Finland, Poland and Spain, with the 6-month to 5-year-old children receiving two 3 µg doses, compared to 10 µg in children aged 5 to 12 years. While the 6- to 24-month-old children had an equivalent immune response to 16- to 25-year-olds (where the vaccine is shown to be highly effective), the 2- to 5-year-olds had an inferior immune response, unfortunately.

This led Pfizer to amend the protocol to add a third dose with the goal to improve the immune response of the 2- to 5-year-olds to that of the 16- to 25-year-olds. This amended clinical trial is not yet completed, so while anticipated that the third dose will improve the immune response, as it has been shown in young adults, this is currently unknown. The clinical trial is expected to be completed in the next few months.

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Dr. William Petri  in the lab headshot

Enter into this equation that the omicron variant that has led to record numbers of children under age 5 hospitalized with COVID-19, suggesting that omicron may not be as mild in these younger children as it is on adults. The FDA asked Pfizer to apply for emergency use authorization prior to the results of the three-dose study are complete. ... Pfizer has followed through with an [emergency use authorization] request. The FDA announced Monday that it is convening its Vaccine and Related Biologic Products Advisory Committee on Feb. 15 to discuss the request for emergency use authorization of the Pfizer-BioNTech COVID-19 Vaccine for use in children 6 months through 4 years of age. The data that the committee will be evaluating will be released to the public no less than two days prior to the meeting, and the meeting itself will be live-streamed on YouTube.

My take on this is that this is a good thing to move forward with evaluation of the safety and efficacy of the two-dose vaccine in the 6-month to 4-year-old children. The review will be conducted in public so that everyone can see the data, and if the Vaccine Advisory Committee judges that EUA should be granted, there are still independent reviews of the vaccine by the full FDA, the independent Advisory Committee on Immunization Practices and, finally, the CDC. So there are a lot of checks and balances to ensure the correct decision is reached.

Q. Can you walk us through how these vaccines were tested for safety? 

A. Safety data will be released by the FDA in advance of the Feb. 15 Vaccine Advisory Committee meeting, so we will all see the safety data then. What has already been published in the New England Journal of Medicine on Jan. 6 is the safety data for the same vaccine (at the higher dose of 10 µg) in children 5 to 11 years of age. ... The vaccine was approximately 95% effective at preventing COVID-19, which at the time, was predominantly the delta variant.

Q. Many parents are struggling with frequent day care closures due to COVID outbreaks. Will CDC guidelines mandating these closures likely change once children under 5 are fully vaccinated?

A. If vaccination is required for staff and children in day care, then one would anticipate that closures due to COVID-19 will be a thing of the past.

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Q. What is the efficacy for this vaccine? And how quickly will a child begin showing immunity against COVID after becoming fully vaccinated?

A. With older children, we know, seven days after receiving the second dose, that the vaccine was approximately 95% effective at preventing COVID-19 from the delta variant. With two doses in children 2 to 5 years of age where the immune response is less, and with the omicron variant, one would anticipate that the vaccine will be less effective, with some unpublished estimates of 50% to 60% effective.

The thought of the FDA, I believe, is that the clinical trial testing of the third dose will be completed in time for the children to receive that third dose, should it be proven safe and effective.

Q. Will young children also need booster shots in the future, roughly five to six months after full vaccination?

A. The mRNA vaccines are moving to a three-dose set of primary vaccinations or shots for all age groups, so, yes, most likely a third dose will be needed.

Q. Do children need to be vaccinated if they’ve already had COVID-19?

A. The degree to which vaccination will enhance naturally acquired immunity from omicron is not known, athough for prior variants, there was added protection by vaccination. Booster vaccinations will, in all likelihood, become part of the landscape of childhood vaccinations in any case, as immunity to coronavirus is short-lived and not lifelong.  

Q. Can COVID vaccines be given to children along with their regularly scheduled vaccinations?

A. Yes, the COVID vaccine will become incorporated into the schedule of childhood vaccinations.

Q. After authorization, how quickly do you expect this vaccine to be readily available in Charlottesville? 

A. There should be little in the way of delay, as although the dose is different than the currently used vaccines, there is no shortage overall of the Pfizer BioNTech vaccine in the U.S.

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Andrew Ramspacher

University News Associate University Communications