Pfizer has said it will begin testing its COVID-19 vaccine in a larger group of children below 12 years of age after selecting a lower dose of the shot in an earlier stage of the trial.
The study will enrol up to 4,500 children at more than 90 clinical sites in the United States, Finland, Poland and Spain, the pharma company said.
The vaccine made by Pfizer and its German partner BioNTech is already authorised for emergency use in anyone 12 and older in the US, Canada and the European Union. They receive the same dose as adults: 30 micrograms.
Enrolment of five- to 11-year-olds for the new study began this week. Based on safety, tolerability and the immune response generated by 144 children in a phase I study of the two-dose shot, Pfizer said it will test a dose of 10 micrograms in children between five and 11 years of age, and 3 micrograms for the age group of six months to five years.
A Pfizer spokesperson said the company expects data from five-to-11-year-olds in September and would likely ask regulators for emergency use authorisation later that month. Data for children two to five years old could arrive soon after that, he said.
Pfizer expects to have data from the six-month to two-year-old age group sometime in October or November.
Nearly seven million teens have received at least one dose of the vaccine in the US, according to the US Centers for Disease Control and Prevention (CDC).
Inoculating children and young people is considered a critical step towards reaching “herd immunity” and taming the COVID-19 pandemic.
Still, scientists in the US and elsewhere are studying the possibility of a link between heart inflammation and mRNA vaccines, particularly in young men. Both Pfizer and Moderna Inc’s vaccines are mRNA shots.
Israel’s Health Ministry said last week it had found the small number of myocarditis cases observed mainly in young men who received the Pfizer vaccine there were probably linked to their vaccination. The cases were generally mild and did not last long.
Pfizer has said it is aware of the Israeli observations of myocarditis and that no causal link to its vaccine has been established.
Separately on Tuesday, the European Union’s drug regulator said it expects to give a verdict on the use of Moderna’s COVID-19 vaccine in 12- to 17-year-olds next month, following an application by the drugmaker.
The two-dose vaccine is already being used in the EU for people above 18 years of age in several countries. The company has also sought approval in Canada for use in adolescents and plans for a US application.
If approved, Moderna’s vaccine would become the second shot cleared for use in teenagers in the EU after Pfizer and BioNTech’s vaccine was given the green light last month.
A European Medicines Agency (EMA) committee would speed up the assessment of data submitted with the application, the regulator said, adding that a delay would happen if the EMA required any additional information.