People with conditions such as leukaemia, advanced HIV and recent organ transplants who are over the age of 12 will be given a third jab following a recommendation from the Joint Committee on Vaccination and Immunisation (JCVI).

The announcement is separate to any decision on a booster programme, but it is understood news on that is expected soon.

Giving its recommendation on Wednesday, the JCVI said people who were severely immunosuppressed at the time of their first or second dose of vaccine may 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, and 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.

Both of these jabs are mRNA vaccines and almost all of the data so far on third doses is based on this kind of vaccine.

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 on that.

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.”

The recommendation does not apply to all those considered clinically extremely vulnerable, but is estimated to include between 400,000 and 500,000 people, or less than 1% of the population.

Mr 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.”

Here is the list given by the JCVI regarding those who should receive a third Covid vaccine dose:

1. Individuals with primary or acquired immunodeficiency states at the time of vaccination due to conditions including:

  • acute and chronic leukaemias, and clinically aggressive lymphomas (including Hodgkin’s lymphoma) who were under treatment or within 12 months of achieving cure

  • individuals under follow up for chronic lymphoproliferative disorders including haematological malignancies such as indolent lymphoma, chronic lymphoid leukaemia, myeloma, Waldenstrom’s macroglobulinemia and other plasma cell dyscrasias (note: this list is not exhaustive)

  • immunosuppression due to HIV/AIDS with a current CD4 count of <200 cells/µl for adults or children

  • primary or acquired cellular and combined immune deficiencies – those with lymphopaenia (<1,000 lymphocytes/ul) or with a functional lymphocyte disorder

  • those who had received an allogeneic (cells from a donor) or an autologous (using their own cells) stem cell transplant in the previous 24 months

  • those who had received a stem cell transplant more than 24 months ago but had ongoing immunosuppression or graft versus host disease (GVHD)

  • persistent agammaglobulinaemia (IgG < 3g/L) due to primary immunodeficiency (for example, common variable immunodeficiency) or secondary to disease/therapy

2. Individuals on immunosuppressive or immunomodulating therapy at the time of vaccination including:

  • those who were receiving or had received immunosuppressive therapy for a solid organ transplant in the previous 6 months

  • those who were receiving or had received in the previous 3 months targeted therapy for autoimmune disease, such as JAK inhibitors or biologic immune modulators including B-cell targeted therapies (including rituximab but in this case the recipient would be considered immunosuppressed for a 6-month period), T-cell co-stimulation modulators, monoclonal tumour necrosis factor inhibitors (TNFi), soluble TNF receptors, interleukin (IL)-6 receptor inhibitors, IL-17 inhibitors, IL 12/23 inhibitors, IL 23 inhibitors (note: this list is not exhaustive)

  • those who were receiving or had received in the previous 6 months immunosuppressive chemotherapy or radiotherapy for any indication

3. Individuals with chronic immune-mediated inflammatory disease who were receiving or had received immunosuppressive therapy prior to vaccination including:

  • high-dose corticosteroids (equivalent to ≥ 20mg prednisolone per day) for more than 10 days in the previous month

  • long-term moderate dose corticosteroids (equivalent to ≥10mg prednisolone per day for more than 4 weeks) in the previous 3 months

  • non-biological oral immune modulating drugs, such as methotrexate >20mg per week (oral and subcutaneous), azathioprine >3.0mg/kg/day, 6-mercaptopurine >1.5mg/kg/day, mycophenolate >1g/day in the previous 3 months

  • certain combination therapies at individual doses lower than above, including those on ≥7.5mg prednisolone per day in combination with other immunosuppressants (other than hydroxychloroquine or sulfasalazine) and those receiving methotrexate (any dose) with leflunomide in the previous 3 months

4. Individuals who had received high-dose steroids (equivalent to >40mg prednisolone per day for more than a week) for any reason in the month before vaccination.

GPs and consultants will be involved in identifying eligible patients and delivering jabs, with more details to be set out.

No decision has been given on any extension of the vaccine programme to include all healthy 12 to 15-year-olds.