The rollout of the Covid vaccine has been speedy to say the least, with well over 12 million jabs distributed in the UK so far.

At the pace it’s going, there have been murmurings that most could receive a vaccination by the end of this year. But one cohort missing from any vaccine conversations up until now has been children.

On Wednesday, a mother appeared on ITV News with a question for England’s deputy chief medical officer, Professor Jonathan Van-Tam. Judith Reekie, who has a clinically extremely vulnerable child, asked: “How do you plan to protect them whilst allowing them to partake within society. Will they be vaccinated?”

Prof Van-Tam responded that the Joint Committee on Vaccination and Immunisation (JCVI) has been “very clear” that children who are extremely clinically vulnerable can be considered for vaccination.

But he stressed it’s “a decision that needs to be taken individually between the parents and the child after discussion”. This is because the vaccines are not currently licensed for use in children.

“Now that shouldn’t put you off,” he said. “If your doctor agrees with you that it’s the right thing for your son or daughter to be vaccinated because of their vulnerability, but it is … always an individual decision when you’re using medicines and vaccines outside of the label.”

Why are the available vaccines not given to children?

The vaccines issued in the UK are suitable for different age groups. The Pfizer/BioNTech vaccine is suitable for people aged 16 and over, while the AstraZeneca/Oxford vaccine and Moderna vaccines, which will be available in March, should be given to over-18s.

This is because the safety and efficacy of these vaccines in younger people and children have not yet been established.

The number one role of the vaccine is to prevent severe disease and death from Covid-19 – and the aim will be the same in any vaccine issued to children. There may also be an additional benefit of the vaccines reducing transmission.

As studies have found children have a reduced risk of experiencing either severe illness or death from Covid-19, they are considered a lower priority for the vaccine than the elderly or those with underlying conditions.

But children aren’t untouchable. Hundreds of children in the UK are struggling with long Covid months after becoming sick and, in rare instances, some children have developed a multi-system inflammatory syndrome linked to Covid-19 which can lead to organ damage. 

Are trials in children underway?

With the Pfizer vaccine, trials are underway involving 2,259 young people aged 12 to 15 years old, however the study results are yet to be shared.

A spokesperson tells HuffPost UK that moving below 12 years of age will require a new study and potentially a modified formulation or dosing schedule of the vaccine. This could mean a delay in getting a vaccine to younger kids.

In December, Moderna pressed go on its own trial of the vaccine in 12- to 17-year-olds, but in January, USA Today reported the company had been struggling to find enough teen volunteers for its trials.

A spokesperson for the Covid-19 Vaccine Team at Oxford University’s Vaccine Centre said trials of the Oxford/AstraZeneca vaccine in children have not yet begun, as the studies are still being designed. 

Oxford Vaccine Centre’s spokesperson couldn’t say whether the dose would need to be tweaked for use in children as the trials are still being designed, however they pointed out that generally, studies in children use the same or a slightly lower dose depending on their age and the vaccine in question.

Another trial is set to start in the UK that will calibrate the correct dose for children and ensure the vaccine is safe. Professor Adam Finn, the deputy chairman of the joint committee on vaccination and immunisation, told the Today programme in January: “We are just starting studies right now, initially in teenagers and then in younger children with the existing vaccines.

“We need to know we’re giving the right dose to the younger children, we need to know that they’re safe, and that information needs to come in before we start using them.”

So when will vaccines be available for children?

Prof Finn said: “I think we will see vaccines being used in children later in the year, almost certainly.” Prof Van-Tam agrees the end of the year seems feasible.

“I believe most of the major manufacturers are starting to turn their attention to, ‘can we do some clinical trials to prove our vaccines are safe and effective in children’,” he told ITV News. “It is perfectly possible that we will have some licensed children’s vaccines for Covid-19 by the end of the year. It is perfectly possible, but not assured.”

In the meantime, the Medicines and Healthcare products Regulatory Agency (MHRA) confirmed to HuffPost UK that approved Covid-19 vaccines can currently be used off-label, meaning they can be given to children in exceptional circumstances.

MHRA chief executive Dr June Raine said a vaccine is likely to be permitted for children where the view of the prescriber is that “the patient’s health is likely to be in jeopardy unless the vaccine is administered”. 

“This is standard practice and brings approved Covid-19 vaccine conditions in line with those of other medicines,” she said.