Scientists at the US Food and Drug Administration, FDA, have said that the likely benefits of giving the Pfizer-BioNTech Covid-19 vaccine to 5 – 11-year-olds clearly outweigh the risks of rare cases of heart inflammation.
On Friday, the vaccine makers said their shot showed 90.7 percent efficacy against the coronavirus in a clinical trial of children aged 5 -11 years old.
The details were in briefing documents published ahead of a meeting of a panel of external experts scheduled to vote on Tuesday whether to recommend that the FDA authorise the shots for the age group.
If the FDA grants the authorisation, the Pfizer-BioNTech would be the first Covid-19 vaccine approved for this age group. Both the Pfizer-BioNTech and Moderna vaccines have been linked to rare cases of heart inflammation called myocarditis, especially in young men.
The FDA said that, assuming the number of myocarditis cases observed in the younger age group would be similar to that seen in 12- to 15-year-olds, the number of Covid-19-related hospitalisations prevented would outnumber myocarditis-related hospitalisations in most scenarios analysed.
Pfizer said the rate of myocarditis in the age group was likely to be lower than observed in vaccinated 12- to 15-year-olds, in part because the younger children were given a lower dose.
The 5 – 11-year-olds were given two shots of a 10mcg dose, a third of what was given to people 12 years and older, 16 children in the trial who had received a placebo got Covid-19, versus three who were vaccinated, Pfizer said in briefing documents submitted to the FDA.
More than twice as many children in the 2,268-participant trial were given the vaccine than placebo, equating to better than 90 percent efficacy.
Pfizer’s clinical trial in 5 -11 years old was not primarily designed to measure efficacy against the virus. It compared the amount of neutralising antibodies induced by the vaccine in the children to the response of older recipients in their adult trial.
Based on the results, the Pfizer-BioNTech Covid-19 vaccine induced a robust immune response in the children and met the FDA’s criteria for the immune response it generated in the children.
The company said that it had expanded its clinical trial to improve its safety data, more than doubling the number of children enrolled.
According to Pfizer, the adverse event profile in the expanded group did not suggest any new safety concerns from the vaccine. It said previously that the safety profile in the age group was generally comparable to that for 16- 25-year-olds.
The second cohort of children have been observed for a shorter time. All of them had received their second dose and more than 70 percent were more than two weeks post-dose two.
The Pfizer-BioNTech vaccine is certified for use in Nigeria by the National Agency for Food and Drug Administration and Control, NAFDAC. Recently the US donated over 3.5 million doses of the vaccine to Nigeria.