Boris Johnson has called on schoolchildren eligible for the coronavirus vaccine to be jabbed before the new term as bookings open for 12 to 15 year-olds to get their second dose.
Appointments for children in this age group for their follow-up jab can be made from Monday in England, the Prime Minister said.
He encouraged all young people entitled to a vaccine to take up the offer before they return to their desks after Christmas.
Last month, the Joint Committee on Vaccination and Immunisation (JCVI) said children aged 12 to 15 should be offered a second dose of the vaccine 12 weeks after the first jab.
The rollout for first doses to this age group in England began on September 20, and the figure stood at 54% unvaccinated up to December 5.
Meanwhile, parents have been urged not to take their children out of school before term ends.
The Prime Minister’s official spokesman said it is “important” that schools and parents “don’t take precautionary steps to deprive their children of education”.
The plea comes amid reports that parents are choosing to keep their children out of class ahead of Christmas due to concerns about the Omicron variant.
Some schools and colleges have switched to remote lessons this week in the run-up to the festive break.
The Prime Minister’s official spokesman said: “The best place for children – who have in many respects suffered the most through this pandemic – is in school, receiving vital face-to-face education.”
This was up from 208,000 children, or 2.6% of all pupils, on November 25.
But school leaders have warned of even worse attendance levels due to Covid-19 in recent days as the Omicron variant has spread further before Christmas.
Paul Whiteman, general secretary of school leaders’ union NAHT, said: “We agree that children should be in school and not missing out on education.
“But if parents feel nervous about sending their children into classrooms due to the soaring levels of Covid, that is an indication that the Government needs to do more to control the spread of the virus.
“The Government can’t simply say that parents must send their children to school without taking the necessary action to reassure them that it is safe for them to do so.”
Abingdon and Witney College in Oxfordshire has also moved the majority of its lessons online this week as a “proactive measure” to reduce the number of people at their campuses in the run-up to Christmas.
Geoff Barton, general secretary of the Association of School and College Leaders, said: “We’re sure that neither schools nor parents need lectures from Downing Street.
“Everybody is doing their very best to keep education going as best they can in increasingly difficult circumstances and amidst endless and unhelpful speculation.
“We agree that the best place for children is in school but we are also conscious that there are very high rates of infections in many settings and areas which are causing huge disruption.
“The Christmas holiday is only a couple of days away and it would be nice to get there without any more finger-wagging.”