Cancer patients may not be protected to the same degree as the rest of the population after they receive their first of two doses of a COVID-19 vaccine, a new UK study has found on March 11.

A team of experts from King's College London and Francis Crick Institute found in the first real-world study of its kind that a shorter than the stipulated 12-week gap between the two vaccine doses for such patients appeared to be the answer. The study's senior authors, Dr Sheeba Irshad and Professor Adrian Hayday believe that there should be an urgent re-evaluation of UK policy for the dosing interval for all cancer patients, and likewise for many other high-risk groups of immuno-suppressed patients.

"Our data provides the first real-world evidence of immune efficacy following one dose of the Pfizer vaccine in immunocompromised patient populations", said Dr Sheeba Irshad, a senior clinical lecturer from the School of Cancer and Pharmaceutical Sciences at King's College London. "We show that following the 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," she said.

Data from the world's first reported trial to examine the level of immune protection after the Pfizer/BioNTech vaccine in cancer patients has found that anti-SARS-CoV-2 the virus which causes COVID-19 antibody responses at week three following the first dose of the vaccine were only 39 per cent and 13 per cent in the solid and haematological cancers, compared to 97 per cent in those without cancer. The preprint study, which is to be peer-reviewed, also reports that when the second dose of the vaccine was given three weeks after the first dose, the immune response improved significantly for solid cancer patients with 95 per cent of them showing detectable antibodies to the SARS-CoV-2 virus within just two weeks.

By contrast, those who did not get a vaccine boost at three weeks did not see any real improvement, with only 43 per cent of solid cancer patients and 8 per cent of blood cancer patients developing antibodies to the Pfizer vaccine at five weeks compared to 100 per cent of healthy controls. The evidence of vaccine responses in cancer patients shows that a gap of 12 weeks between doses of the Pfizer-BioNTech vaccine could leave many cancer patients vulnerable to serious COVID-19, the study finds. Prof. Adrian Hayday from King's College London and the Francis Crick Institute said: 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.

Dr Simon Vincent, Director of Research, Support and Influencing at Breast Cancer Now, called on the Joint Committee on Vaccination and Immunisation (JCVI), which determines the UK's vaccine rollout cohorts, to urgently review the evidence and to consider adapting its strategy to ensure that cancer patients can receive both the first and second dose of the Pfizer/BioNTech COVID-19 vaccine within a three-week timeframe to minimise their risk of both contracting and becoming seriously ill with coronavirus.

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-19 vaccine, and then do not receive their vaccine boost in the following three weeks, he said. But Cancer Research UK said the small study had not yet been reviewed by other scientists and people undergoing cancer treatment should continue to follow the advice of their doctors, while the government said that antibody response "was only part of the protection provided by the vaccine". Meanwhile, the UK study will continue to follow cancer patients after their vaccinations for up to six months.