Half a million people with severely weakened immune systems are to be offered third Covid vaccine shots in a move that will increase debate over the rollout of booster jabs for the wider population. The NHS will provide third doses for those aged 12 and up who have severely compromised or suppressed immune systems at a time decided by their clinicians. It follows a recommendation on Wednesday from the government’s Joint Committee on Vaccination and Immunisation (JCVI). Health officials said the shots were not boosters, which are given to prolong people’s protection, but instead form part of the primary vaccination schedule for 400,000 to 500,000 vulnerable UK patients. Among people with impaired immune systems, these are the estimated 40% who cannot mount a strong response even after two shots of vaccine, according to the recent Octave study. Those eligible include people with particular diseases such as HIV and blood cancer, which can impair the immune system, and those on medication that damps down immunity, for example to prevent the body rejecting transplanted organs. GPs and consultants will decide on a case-by-case basis when individual patients are most likely to mount the best response to the extra shot, for example before they embark on chemotherapy rather than afterwards. People with impaired or suppressed immune systems are more likely to be severely ill if they contract the virus. The move was announced as the UK recorded 207 deaths within 28 days of a positive Covid test, the highest daily total since 9 March – though the bank holiday weekend is likely to have affected the total. There were 35,693 new cases and 842 people hospitalised. In June, the JCVI urged the NHS to prepare for a two-stage booster programme starting in September, pending a final decision in the summer, but so far none has been forthcoming. The JCVI is understood to be awaiting more data on the benefits of pressing ahead but many senior scientists, including Prof Sir Andrew Pollard of the Oxford Vaccine Group, argue that more people will die around the world if rich western countries prioritise boosters. Explaining the justification for third doses, Prof Wei Shen Lim, chair of the JCVI’s Covid-19 immunisation group, 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 UK has relied heavily on the Oxford/AstraZeneca vaccine, but citing greater evidence the JCVI recommends that third shots of Pfizer/BioNTech be given to those aged 12 to 17 and either Pfizer/BioNTech or NIH/Moderna for adults aged 18 and over. The same patients, and those with less serious immune conditions, may also be offered boosters when the JCVI reaches a final decision on the programme. The health secretary said the NHS would 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,” Sajid Javid said. “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.” Prof Iain McInnes, the leader of the Octave and Octave Duo studies and vice-principal of the University of Glasgow, said the JCVI decision on third shots for those with severely weakened immune systems was welcome. “People with chronic diseases who have a weakened immune system are understandably worried that they will have lower levels of protection from Sars-CoV-2 vaccination,” he said. “This news will undoubtedly offer reassurance for people with immunosuppression and those with weakened immune systems.” Gemma Peters, the chief executive of Blood Cancer UK, said: “People with blood cancer are at higher risk of becoming seriously ill from Covid and are less likely to have responded well to two doses of the vaccine, so it is great news that they will now be offered a third dose. “The NHS now needs to make sure it contacts every person with blood cancer to invite them for a third dose. In the past, too many people with blood cancer have been missed out in this sort of blanket communication and it is vital that this time everyone gets an invitation promptly.”