Pfizer and BioNTech Amend Clinical Trial Design to Evaluate Booster Dose of COVID-19 Vaccine in Children Aged 6 Months to 5 Years

On December 17, 2021, Pfizer and BioNTech announced that they would modify a large clinical trial evaluating their COVID-19 vaccine for children aged 6 months to 5 years. This sub-study will assess the efficacy and safety of a third 3 µg dose administered at least two months after the second dose in participants who have completed the two-dose primary series. If this trial yields positive results, Pfizer and BioNTech expect to submit data to regulators in the first half of 2022 to seek Emergency Use Authorization (EUA) for a COVID-19 vaccine booster for children aged 6 months to 5 years.

This large clinical trial enrolled 4,500 children aged 6 months to under 12 years (regardless of prior evidence of SARS-CoV-2 infection) to evaluate the safety, tolerability, and immunogenicity of the Pfizer/BioNTech vaccine two-dose regimen (administered approximately 21 days apart) across three age groups (5 years to under 12 years; 2 years to under 5 years; 6 months to under 2 years). Based on the dose-escalation phase of the trial, in the Phase 2/3 trial, children aged 5 years to under 12 years received a two-dose regimen at 10 µg per dose, while children under 5 years received a lower dose level of 3 µg per dose.

Although the trial is still ongoing and remains blinded, researchers conducted a pre-specified immunogenicity analysis on a subset of participants one month after the second dose. The results indicated that, compared to the 16-25 age group which demonstrated high immune protection efficacy of the COVID-19 vaccine, the 6-24 months age group met the non-inferiority criteria, but the 2-5 years age group did not. Additionally, no safety issues were identified, and the 3 µg dose level showed a favorable safety profile in the age group of 6 months to under 5 years.

In addition, Pfizer and BioNTech have initiated a sub-study at low dose levels of 10 µg or 30 µg in approximately 600 adolescents aged 12-17 to evaluate the safety and immunogenicity of a third dose of the COVID-19 vaccine. The two companies also plan to assess a 10 µg booster dose in children aged 5 to under 12. These decisions are based on efficacy data from three-dose vaccination in individuals aged 16 and above, as well as early laboratory data observed against Delta and other variants of concern (including Omicron), and have been recognized and agreed upon by the U.S. FDA and the European Medicines Agency (EMA). The data suggest that individuals who have received three doses of the COVID-19 vaccine may achieve a higher level of immune protection.

References:

[1] Pfizer And Biontech Provide Update On Ongoing Studies Of Covid-19 Vaccine. Retrieved December 17, 2021, from https://www.pfizer.com/news/press-release/press-release-detail/pfizer-and-biontech-provide-update-ongoing-studies-covid-19

[2] Pfizer Plans To Study A Third Shot For Its Covid-19 Vaccine In The Youngest Kids, Pushing Back Its Timeline Farther. Retrieved December 17, 2021, from https://endpts.com/pfizer-plans-to-trial-a-third-shot-for-its-covid-19-vaccine-in-the-youngest-kids-pushing-back-its-timeline-farther/

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