Children as young as 6 months could be eligible for Covid-19 vaccination later this month.
The US Food and Drug Administration will meet on June 15 to consider applications by Moderna and Pfizer-BioNTech — companies with a leading role in global inoculation drives — with a decision expected soon after.
Dr Ashish Jha, coronavirus response co-ordinator for the White House, said the US would make 10 million doses from both drug makers available as soon as approval is granted. It is understood this could be as soon as June 21, following federal holidays.
Most under-5s remain unprotected against the virus, more than two years into the pandemic.
There are some exceptions, such as China and the UAE, where children as young as 3 can be vaccinated with a shot made by Sinopharm.
Why are vaccines for under-5s still not widely available?
When vaccines are developed, manufacturers begin trialling them in adults to ensure they are safe and effective before moving down the age groups.
After the rapid spread of Covid-19, priority was given to protecting older and more vulnerable members of society.
The Pfizer-BioNTech vaccine has been available to children over 12 for a year, and for children aged 5 and older since early February in the UAE, having obtained approval in November.
Trials involving the youngest children have been beset by a series of delays, partly because efficacy was affected by the Omicron strain.
Covid is generally mild in children but some do become severely sick.
Omicron has been associated with a surge in cases requiring hospital treatment in children in some countries, including the US, where one study showed the variant caused three times as many hospital admissions compared with previous strains.
The Centres for Disease Control and Prevention said during the peak of the first Omicron wave, children age 4 and under were admitted to hospital at about five times the rate of those infected during the Delta wave, although there were fewer deaths.
At what stage are trials now?
Moderna has already submitted data on its shot for children age 6 months to 5 years to the US Food and Drug Administration.
Trials showed the vaccine was about 51 per cent effective against infection for children under 2, and 37 per cent effective among children 2 to 5. That may seem low, but the effectiveness of all vaccines were affected by the immune-evasive Omicron variant.
Pfizer has also shared its data with the FDA on its own trial for three doses of a vaccine for children aged 6 months to 4 years. It initially hoped to file for authorisation for a two-shot course in February, but the companies behind the shot said they wanted to wait for data about a three-dose course.
Pfizer finished submitting an an application for authorisation based on that data on June 1 and the FDA will meet on June 15 discuss it. If it is approved, experts said it could be made available soon after.
What did Pfizer's trial show?
The vaccine was found to induce a strong immune response, with a good safety profile similar to a placebo, after the third dose, Pfizer said.
Vaccine efficacy was 80.3 per cent but that was based on only 10 symptomatic cases — so it could change.
And the trial protocol specifies that a formal analysis will be carried out when at least 21 cases have occurred seven days after the third dose. Pfizer said final vaccine efficacy data will be shared once available.
When will a decision be made?
The FDA will discuss both vaccines for young children on June 15. If approved soon after, experts say young children could be fully vaccinated in the US with Moderna by late July, or late September with Pfizer, as there is a two-month gap between the second and third dose.
When would vaccines be made available in UAE?
That is not yet known. If the pattern repeats for vaccines for the 5-11 age group, the UAE could follow suit within days of the shots being approved by US regulators, if they are approved.
But they may not be immediately available. Pfizer-BioNTech vaccines approved for children aged 5 and older took about three months to be administered.