NEW YORK • Pfizer said it will begin testing its Covid-19 vaccine in a larger group of children under 12 after selecting a lower dose of the shot in an earlier stage of the trial.
Compared with adults, children are much less likely to develop severe illness following Covid-19 infection.
Nearly four million children in the United States have tested positive for the virus since the start of the pandemic, according to the American Academy of Paediatrics.
The study will enrol up to 4,500 children at more than 90 clinical sites in the US, Finland, Poland and Spain, the drugmaker said on Tuesday.
Based on safety, tolerability and the immune response generated by 144 children in a phase one 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 3mcg for those six months to five years old.
A Pfizer spokesman 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 age group in October or November.
The vaccine - made by Pfizer and German partner BioNTech - has been authorised for use in children as young as 12 in Europe, the US and Canada. They receive the same dose as adults - 30mcg.
Singapore announced last month that it had also approved the use of the Pfizer jab for those aged 12 and above as part of its national vaccination programme.
Nearly seven million teenagers have received at least one dose of the vaccine in the US, according to the US Centres for Disease Control and Prevention.
Inoculating children and young people is considered a critical step towards reaching herd immunity and taming the pandemic.
In March, Moderna began testing varying doses of its vaccine in younger children. The trial aimed to enrol 6,750 healthy children in the US and Canada.
Results are not expected until the end of summer, and the vaccine's authorisation by the US Food and Drug Administration (FDA) will take longer.
"I think it is going to be early fall, just because we have to go down in age very slowly and carefully," Moderna chief executive Stephane Bancel said on Monday.
The company announced late last month that its vaccine was very effective in 12-to 17-year-olds, and it plans to apply to the FDA for authorisation in that age group.
Last week, Moderna also asked the agency for full approval of its vaccine, rather than the emergency use for which it is now authorised.
The company also said on Monday it has partnered with Israeli company Medison Pharma to commercialise Moderna's Covid-19 vaccine in 20 markets across central Eastern Europe and Israel.
Meanwhile, 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's and Moderna's vaccines are mRNA shots.
The US will not be the first country in the world to authorise a coronavirus vaccine for young children. China has approved Sinovac's vaccine for children as young as three, according to the company's chairman.
The approval has not been officially announced.
REUTERS, NYTIMES
