British people with severely weakened immune systems are to get an additional Covid jab as a booster to help keep infections at bay.
The UK government’s decision to accept a recommendation from experts will mean around half-a-million immunocompromised people will be offered a third dose of a coronavirus vaccine.
The Joint Committee on Vaccination and Immunisation (JCVI) had told ministers those with conditions such as leukaemia, advanced HIV and recent organ transplants who are over the age of 12 should get an additional jab.
Health secretary Sajid Javid made clear the move did not signal the start of a bigger booster programme for the wider population, but it is understood developments are expected to be announced soon.
Javid said the government was continuing to plan for a booster programme to begin this month and said people most at-risk from Covid-19 would be prioritised for that.
To date, more than 40 million people in the UK have been given two doses of the vaccine, equivalent to just over 64% of the population.
The JCVI said it was still deliberating on the potential benefits of booster vaccines for the rest of the population and was awaiting further evidence to inform its decision.
No decision has been given either on any extension of the vaccine programme to include all healthy 12 to 15-year-olds.
Giving its recommendation on Wednesday, the JCVI said people who were severely immunosuppressed at the time of their first or second dose of vaccine my not have been able to mount a full response to vaccination, meaning they could be less protected than the wider population.
The committee said studies are ongoing to see how effective a third dose is for this group of people. As it is considered unlikely to cause any harm, they have decided that a third jab can be safely offered and might boost protection.
The preference for children in this category who are aged 12 to 17 is the Pfizer vaccine, while those aged 18 and over will be given either Pfizer or Moderna.
The JCVI said the timing of a third dose will be made by a patient’s specialist doctor, but that they would usually be given at least eight weeks after the second dose, with some flexibility.
Professor Wei Shen Lim, chair of Covid-19 Immunisation for the JCVI, said: “We want people with severely suppressed immune systems to have the best chance of gaining protection from Covid-19 via vaccination.
“Therefore, we are advising they have a third vaccine dose on top of their initial two doses, as we hope this will reduce their risk of severe outcomes such as hospitalisation and death.”
Javid said he has accepted the JCVI’s recommendation.
He said: “We know people with specific conditions that make them particularly vulnerable to Covid-19 may have received less protection against the virus from two vaccine doses. I am determined to ensure we are doing all we can to protect people in this group and a third dose will help deliver that.
“The NHS will contact people as soon as possible to discuss their needs and arrange an appointment for a third dose where clinically appropriate.
“This is not the start of the booster programme – we are continuing to plan for this to begin in September to ensure the protection people have built from vaccines is maintained over time and ahead of the winter. We will prioritise those most at risk to Covid-19, including those who are eligible for a third primary vaccine, for boosters based on the final advice of the JCVI.”
This article originally appeared on HuffPost UK and has been updated.