US health officials have given the final sign-off to Pfizer’s child-size Covid-19 shot, a major expansion of the nation’s vaccination campaign.

The Food and Drug Administration (FDA) had already authorised the shots for children aged five to 11 – doses just a third of the amount given to teenagers and adults.

But the Centres for Disease Control and Prevention (CDC) recommends who should receive FDA-cleared vaccines.

The announcement by CDC director Dr Rochelle Walensky came only hours after an advisory panel unanimously decided Pfizer’s shots should be opened to the 28 million youngsters in that age group.

Millions of shots made by Pfizer and its partner BioNTech have already been shipped to states, doctors’ offices and pharmacies to be ready for the CDC’s decision.