Pfizer plans to study a third shot for its Covid-19 vaccine in the youngest kids, pushing back its timeline farther
American children under the age of five may not be vaccinated until mid-2022, as Pfizer said Friday that it’s going to now test a third dose of its Covid-19 vaccine in the trial.
The decision comes as Pfizer announced non-inferiority was not met for children between the ages of two and five when compared to older teenagers in the current trial.
Pfizer previously said it might apply for an EUA in this youngest population by the end of December or early next year, but now says that if the three-dose study proves successful, Pfizer and BioNTech expect to submit data to regulators to support an EUA “in the first half of 2022.”
The shift to three doses was made after a routine review by the external independent Data Monitoring Committee, and the trial will now evaluate a third dose of 3 µg at least two months after the second dose in this young age group. Here’s how Pfizer explained the non-inferiority issue with the 2- to 5-year-old group in the trial:
While the study is ongoing and remains blinded, a pre-specified immunogenicity analysis was conducted on a subset of the study population one month following the second dose. Compared to the 16- to 25-year-old population in which high efficacy was demonstrated, non-inferiority was met for the 6- to 24-month-old population but not for the 2- to under 5-year-old population in this analysis. No safety concerns were identified and the 3 µg dose demonstrated a favorable safety profile in children 6 months to under 5 years of age.
Pfizer and BioNTech are also shifting to a three-dose regimen for all ages, as the companies plan to evaluate a third dose of the 10 µg formulation in children five to under 12 years of age. Additionally, the companies have initiated a low dose sub-study of a third dose of 10 µg or 30 µg in approximately 600 adolescents aged 12- to 17 to assess safety and immunogenicity.
Initially, the Phase I/II/III trial, which enrolled about 4,500 children aged six months to under 12 years in the US, Finland, Poland and Spain, was designed to evaluate the safety, tolerability and immunogenicity of the Pfizer-BioNTech vaccine on a two-dose schedule (approximately 21 days apart) in three age groups: ages five to under 12 years; ages two to under five years; and ages six months to under two years.
In addition to Pfizer, Moderna is working on its own Covid-19 vaccine trial for those between the ages of six months and 12.
Stephen Hoge, president of Moderna, said in the company’s Q3 earnings call that the company submitted data from its KidCove study to the FDA as well as to other countries.
But Hoge noted that the company was recently notified by the FDA that the agency “will require additional time to evaluate our proposed amendment due to recent analysis of the risk of myocarditis after vaccination in some populations. The agency expects this evaluation may extend until January 2022.”