All children may be offered the Covid vaccine later this year once trials conclude, despite officials being set to stop short of that recommendation on Monday.
The Joint Committee on Vaccination and Immunisation (JCVI) is expected to announce that only vulnerable youngsters between the ages of 12 and 15, and 17-year-olds within three months of their 18th birthday, will be offered a jab amid concerns there is too little data on safety and efficacy in young people.
But the JCVI is expected to leave the door open for more children to be vaccinated once trials conclude later this year, The Telegraph understands.
In June, the Medicines and Healthcare products Regulatory Agency (MHRA) approved the Pfizer jab for 12 to 15-year-olds in Britain following early trial results in teenagers, but there is still no data for younger children.
Pfizer is expected to release results on trials for five to 11-year-olds in September and two to five-year-olds by November, with the company expecting regulator approval within a month of releasing positive data. AstraZeneca is also conducting trials in children aged six to 17, with the British team likely to release results before the end of the year.
On Sunday, experts warned that it may be difficult to reach herd immunity in Britain if children are not vaccinated. Nearly one in five people in the UK are under 16 and, despite everyone being offered a vaccine, around 12 per cent of adults have not had a first jab.
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Prof Neil Ferguson, of Imperial College, a member of the Government’s Scientific Advisory Group for Emergencies (Sage) told the BBC: "In the absence of vaccinating it’s inevitable that we’re going to have very high numbers of cases in teenagers, and we will not be able to reach herd immunity without significant immunity in people under 18."
The JCVI is expected to keep the situation under review and will be watching the results from trials closely.
Scientists are particularly concerned that vaccination may damage the developing immune system of younger children. Different age groups may require different doses, further complicating the rollout, and companies must show it will not make children who get Covid more ill – which has happened with other vaccines in the past.
Experts are also worried that the benefits to children may not outweigh the risks, making vaccination ethically dubious and leaving the Government vulnerable to legal challenges.
The scientific community is divided on whether it is better to allow children to catch Covid when they are at little risk from the virus, allowing them to build natural immunity, or vaccinate early. However some countries, such as Israel and the US, have already started vaccinating children as young as 12.
On Sunday, Robert Jenrick, the Housing and Communities Secretary, said the Government was expecting advice from JCVI imminently.
He told the Sky News Trevor Phillips on Sunday programme: "We will be looking carefully at their advice when we receive it – we expect it very soon – on whether or not we should open up the vaccine programme in the first instance to those children who are just short of their 18th birthday, to those children who have particular vulnerabilities and those children who are in households where there are people who are particularly vulnerable.
"That seems a sensible way for us to proceed, but ministers will have to make that decision when they are armed with the final advice from the JCVI."
A Department of Health spokesman said: "The Government will continue to be guided by the advice of the JCVI, and no decisions have been made by ministers on whether people aged 12 to 17 should be routinely offered Covid vaccines."