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Photo of masked woman receiving post-vaccination plaster.

MRC Weatherall Institute of Molecular Medicine researchers have found that antibody responses to the first doses of COVID-19 vaccine in people with chronic myeloid blood cancers are not as strong as those among the general population.

While this is expected to improve with the second dose, this important finding may help influence the design of future vaccination strategies, with further work needed to determine the optimal interval between vaccine doses in certain groups.

The team from the University of Oxford’s MRC-Weatherall Institute of Molecular Medicine (MRC-WIMM) Molecular Haematology Unit studied 60 patients with chronic myeloid blood cancers under the care of the Myeloid Team at the Churchill Hospital, Oxford University Hospitals NHS Foundation Trust.

The study, published in the British Journal of Haematology, was supported by the NIHR Oxford Biomedical Research Centre.

These patients had a variety of blood cancers, including: chronic myeloid leukaemia (CML), essential thrombocythemia (ET) polycythaemia (PV), myelofibrosis (MF) and myelodysplastic syndromes (MDS). As these cancers do not involve the antibody-producing B cells in the blood, antibody responses might be expected to be reasonably normal.

Their antibody levels were measured after they had received their first dose of the COVID-19 vaccine. Most patients developed antibodies in response to the vaccination, and the Pfizer and Oxford/AstraZeneca vaccines were found to be equally effective.

“We found that the proportion of patients with a detectable antibody response two weeks after the first vaccine dose was significantly lower in the patient group than in healthy controls of similar age to the patients,” explained Dr Onima Chowdhury, Consultant Haematologist and one of the lead authors of the study. 

“Around 60 per cent of patients had a positive antibody test after the first dose, compared to 95% of the healthy controls. This difference was particularly marked in patients with myeloproliferative neoplasms who were receiving certain treatments, while other subgroups such as patients treated with interferon or those with chronic myeloid leukaemia responded almost as well as the controls.”

Fellow author Dr Beth Psaila, Cancer Research UK Advanced Clinician Scientist at the MRC-WIMM and Oxford BRC Senior Fellow, said: “The COVID-19 pandemic has had a severe impact on patients with blood cancers, and the roll-out of the vaccines has been hugely important to enable vulnerable individuals to emerge from shielding.

“However, given that patients with cancer were not included in the initial trials of the COVID-19 vaccines, it is important that we carefully analyse responses to ensure that patients who are vulnerable to severe infection are optimally protected.

Dr Psaila added: “This study showed that in certain patient groups, responses to the first vaccine dose were disappointing. However, we are continuing to study responses to the second ‘booster’ dose and are now working collaboratively with other UK centres as part of a taskforce coordinated by Blood Cancer UK to shed more light on these findings in larger cohorts of patients, and to carefully study the impact of certain treatments on immunity in patients with myeloid blood cancers.”

Dr Chowdhury concluded: “Although responses to the booster doses are encouraging, and severe COVID-19 infections appear to be rare in patients following vaccination, our finding that responses to the first dose may be impaired in this particular patient group was unexpected and may help guide optimal design of vaccination schedules in efforts to ensure that all vulnerable patients are adequately protected from severe COVID-19 infection.”