Research of more than 150 patients found the jab stimulated an antibody response in just 39 per cent of people with solid cancers, such as in the breast or prostate, after three weeks.
The single dose was even less effective in blood and bone marrow cancer patients, with just 13 per cent developing the virus-fighting proteins, compared to 97 per cent of healthy people.
The King’s College London study found that when patients were given the booster dose at 21 days, the percentage who showed signs of immunity more than doubled to up to 95 per cent.
Antibodies are not the only part of the immune response to Covid — white blood cells also play an important role. But having no detectable levels strongly suggests someone has little protection.
Cancer charities and scientists who led the research are urgently calling for Britain’s 2million cancer patients to get their second injection sooner.
Under the current UK dosing regimen, Britons are being offered their second dose after 12 weeks on the advice of the Government’s expert advisory group on vaccines.
Cancer patients are among the most vulnerable to dying from Covid and reliant on a vaccine because their immune system is already compromised. They are also normally on immunosuppressant drugs, which make it even more difficult for their bodies to naturally defend against the virus.
More than half of cancer patients are not protected against coronavirus after a single dose of the Pfizer vaccine, an alarming study has found (file)
The study didn’t look at Oxford University’s coronavirus vaccine, which works slightly differently. But both of Britain’s approved jabs have similar success rates.
Professor Adrian Hayday, an immunologist at King’s, said: ‘The vaccine is very impressive in its impact on healthy individuals and our study shows that it can clearly bring immense benefit to cancer patients too, but in most cases this is only after boosting.
‘Cancer patients should be vaccinated and boosted quickly and their responses, particularly those of blood cancer patients, should be intensively monitored so that those who mix with family, friends and carers can be confident of their environment.’
Up to 10 million extra vaccine doses could be available to UK within days as surge in supply boosts roll-out
Up to 10 million extra vaccine doses could be available to the UK within days following a surge in supply, in another major boost for the country’s vaccine roll-out.
As the number of Britons having had their first Covid jab last night topped 22 million, figures revealed the Scottish Government now has access to around 900,000 unused doses.
Though the Government has so far refused to give data on its vaccine supply, the figure from Scotland, which is given a share of the UK’s total jab stockpile, means the total across Britain could be up to 10 million.
The boost means the UK could increase the rate it gives out second doses, without impacting on the rate it is giving out the first doses. It will also be a boost to hopes that the Government can extend the roll-out to all over 50s later this month.
It comes as Wales’ First Minister Mark Drakeford last night alleviated fears of over a ‘dip’ in the vaccination.
He told the i newspaper that the dip was now over, as the UK prepares to enter what he described as a ‘crucial stage’ of its jab rollout.
Mr Drakeford said: ‘We are confident that we are past the couple of weeks where there was a dip in supply and we will be getting significantly greater volumes during the month of March.’
Last month the country’s highly-praised vaccination roll-out began to stall after getting off to a rapid start – which put the UK far ahead of its European neighbours.
Just 192,000 people were vaccinated on Monday, February 23 and 142,000 the day before, in two of the lowest daily tolls since the mammoth operation began to gather steam at the start of the year.
Ministers have repeatedly blamed the ‘lumpy’ supply of vaccines as being the ‘rate-limiting factor’ of the programme.
Dr Simon Vincent, director of research, support and influencing at Breast Cancer Now, described the study as ‘worrying’ and called on an urgent rethink to the vaccine programme.
He added: ‘Worryingly, this study suggests that people affected by cancer, including breast cancer, get little protection against the virus when they only receive a single dose of the Pfizer Covid vaccine, and then do not receive their vaccine boost in the following three weeks.
‘In contrast, the study identifies that when patients received a second dose of the vaccine within three weeks, they had significantly improved immune response and protection against coronavirus.
‘In light of these findings we are calling on the Joint Committee on Vaccination and Immunisation to urgently review the evidence presented in this study, and to consider adapting its strategy to ensure that people who may benefit from this approach, including those with breast cancer, receive both the first and second dose of the Pfizer Covid vaccine within a three week timeframe to minimize their risk of both contracting and becoming seriously ill with coronavirus.’
The KCL study, which has not yet been published in a scientific journal, looked at 151 cancer patients and 54 healthy controls. It was done in collaboration with the Francis Crick Institute in London.
Researchers took antibody levels from cancer patients and healthy volunteers three weeks after getting the first dose.
They found 97 per cent of health people had antibodies, compared to just 39 per cent of patients with solid cancers and 13 per cent of those with blood cancers.
Forty-seven cancer patients were given their second dose later that day at Guy’s and St Thomas’ NHS Foundation Trust, King’s College Hospital or Princess Royal University Hospital in Bromley.
Antibody levels were then retested at five weeks in all three groups: cancer patients given both doses, cancer patients who had the second injection delayed and healthy participants not given the booster jab.
Results showed 95 per cent of patients with solid cancers given both doses had detectable antibodies. For those with blood cancers the sample size was too small but there was a ‘noticeable improvement’, researchers said.
Every healthy participant who received one dose tested positive for the proteins.
And among those cancer patients who had the booster shot delayed, 8 per cent of blood cancer patients had antibodies. The figure was 43 per cent in solid cancer patients.
The trial will continue to follow cancer patients post vaccination for up to six months to see how antibody levels chance over time on various dosing regimens.
Dr Sheeba Irshad, a senior clinical lecturer from King’s College London who co-led the study, said: ‘Our data provides the first real-world evidence of immune efficacy following one dose of the Pfizer vaccine in immunocompromised patient populations.
‘We show that following first dose, most solid and haematological cancer patients remained immunologically unprotected up until at least five weeks following primary injection; but this poor one dose efficacy can be rescued with an early booster at day 21.
‘Based on our findings, we would recommend an urgent review of the vaccine strategy for clinically extremely vulnerable groups.
‘Until then, it is important that cancer patients continue to observe all public health measures in place such as social distancing and shielding when attending hospitals, even after vaccination.’