Pfizer and BioNTech said Thursday that they have started testing their COVID-19 vaccine BNT162b2 in children ages 6 months to 11 years old, with initial results expected in the second half of the year. The mRNA-based vaccine is currently authorized for people 16 years and older in multiple markets, including the UK, US and EU, and the companies began testing it in adolescents ages 12 years to 15 years a few months ago.
“Children under the age of 15 account for 26% of the global population,” Pfizer noted, adding “we believe successfully vaccinating children will contribute to protection against COVID-19 if the vaccine proves to be effective in that population.”
Pfizer’s latest paediatric trial is a phase 1/2/3 dose-escalation study that will recruit up to 4,644 healthy children in the US and Europe to evaluate BNT162b2 versus placebo on a two-dose schedule given approximately 21 days apart. Researchers will initially evaluate doses in children ages 5 to 11 years before moving on to children who are 2 to 5 years, and finally to those 6 months to 2 years old. According to Pfizer, vaccine effectiveness will be inferred through “immune-bridging” to the subgroup of people aged 16 to 25 who were in the pivotal phase 3 trial for BNT162b2.
Adolescent trial readout due in weeks ahead
“We hope to receive authorization for vaccination of these younger kids by early 2022,” the company said, adding that children younger than 6 months of age may also eventually be evaluated, once an acceptable safety profile has been established. CEO Albert Bourla indicated recently that Pfizer expects to submit data from the trial evaluating BNT162b2 in children 12 to 15 years old to regulatory authorities in the coming weeks.
Moderna last year started testing its COVID-19 vaccine mRNA-1273 in children 12 years and older, and recently also began dosing those aged six months to 12 years in a phase 2/3 trial, while AstraZeneca has been studying its candidate AZD1222 in children ages 6 years to 17 years in the UK since February. For its part, Johnson & Johnson has said it is in discussions with regulators to start paediatric testing of its single-dose vaccine Ad26.COV2.S, though it has not provided a timeline.
Meanwhile, Pfizer and BioNTech also began testing BNT162b2 last month in healthy pregnant women over 18. A small study published Thursday in the American Journal of Obstetrics & Gynecology found that mRNA vaccination against COVID-19 was safe and triggered neutralizing antibodies in pregnant and lactating women, and that immune transfer to newborns occurred via placenta and breastmilk.