US Food and Drug Administration staff reviewers on Sunday said Pfizer-BioNTech's Covid-19 vaccines were effective and safe for use in children aged 6 months to 4 years.
The FDA reviewers said in briefing documents published on Sunday evening that their evaluation did not reveal any new safety concerns related to the use of the vaccine in young children.
The FDA analysis of data from Pfizer's trial was published ahead of a June 15 meeting of its outside advisers. Recommendations from the external advisers will determine the FDA's decision on the vaccines.
"Available data support the effectiveness of the Pfizer-BioNTech Covid-19 Vaccine 3-dose primary series in preventing Covid-19 in the age group of 6 months through 4 years," FDA staff said in the review.
An early analysis of data from Pfizer-BioNTech's vaccine based on 10 symptomatic Covid-19 cases identified when the Omicron coronavirus variant was dominant suggested a vaccine efficacy of 80.3% in the under-5 age group.
Covid-19 shots for children under the age of 6 are yet not approved in most parts of the world. It remains unclear how many parents will get their young ones vaccinated as demand has been low for kids aged 5 to 11.
US President Joe Biden's administration expects vaccinations for young children to begin in earnest as early as June 21 if the FDA and the Centers for Disease Control and Prevention approve the vaccines.
Government officials say pre-orders for use in the under-6 age group has been low but demand is expected to pick up once the vaccines gain authorisation.
The FDA on Friday released a staff review of Moderna Inc's Covid-19 vaccine which said the doses were safe and effective for use in children aged 6 months to 17 years old.