The White House’s top infectious disease expert has said the Covid-19 vaccination series for children aged four and under is likely to require three separate doses of Pfizer’s mRNA vaccine.

       Speaking at Wednesday’s White House Covid-19 briefing, Dr Anthony Fauci said the Pfizer shot is currently being tested in two clinical trials — one for children who are six months to two years of age, and another for children aged two to four years.

       But the veteran virologist said the study in the older group has not yet shown the effectiveness standard required for authorisation.

       “Dose and regimen for children 6 months to 24 months worked well, but it turned out the other group from 24 months to 4 years did not yet reach the level of non-inferiority, so the studies are continued,” he said.

       Dr Fauci added that “it looks like” the Pfizer shot will be administered to children in “a three-dose regimen”, but stressed that he was not able to speak for the Food and Drug Administration officials responsible for authorising administration of the shots to young children.

       Recommended The rise of RFK Jr: The anti-vax hero ‘more dangerous’ than ever White House Covid officials rebut anti-vaccine Tucker Carlson guest RFK Jr. apologizes after condemnation for Anne Frank comment

       “We need to be patient — that’s why the system works,” he said. “The FDA is very scrupulous in their ability and in their effort to make sure that, before something gets approved for any age, and especially with children … that they will be safe, and that they will be effective.”