Effectiveness and Safety of COVID-19 Vaccination in People with Blood Cancer

Background: People with blood cancer have increased risk of severe COVID-19 outcomes and poor response to vaccination. We assessed the safety and effectiveness of COVID-19 vaccines against in this vulnerable group compared to the general population. Methods: Individuals aged ≥12 years as of 1st December 2020 in the QResearch primary care database were included. We assessed COVID-19 vaccine effectiveness (VE) in people with blood cancer against COVID-19-related hospitalisation and death using a nested matched case-control study. Using the self-controlled case series methodology, we compared the risk of 56 pre-specified adverse events within 1-28 days of a first, second or third COVID-19 vaccine dose in people with and without blood cancer.Findings: The cohort comprised 12,274,948 individuals, of whom 81,793 had blood cancer. COVID-19 vaccines were protective against COVID-19-related hospitalisation and death in people with blood cancer, although they were less effective, particularly against COVID-19-related hospitalisation, compared to the general population. In the blood cancer population, VE against hospitalisation was 64% (48%-75%) 14-41 days after a third dose, compared to 80% (78%-81%) in the general population. Against COVID-19-related mortality, VE was >80% in people with blood cancer 14-41 days after a second or third dose. We found no significant difference in risk of adverse events 1-28 days after any vaccine dose between people with and without blood cancer.Interpretation: Our study provides robust evidence which supports the use of COVID-19 vaccinations for people with blood cancer.Funding: Blood Cancer UK; John Fell Oxford University Press Research Fund; Cancer Research UK.Declaration of Interest: JHC reports grants from National Institute for Health Research (NIHR) Biomedical Research Centre, Oxford, John Fell Oxford University Press Research Fund, Cancer Research UK and Oxford Wellcome Institutional Strategic Support Fund and other research councils, during the conduct of the study outside the scope of this work. JHC is founder and was shareholder until 9 Aug 2023 of ClinRisk Ltd, which produces open and closed source software to implement clinical risk algorithms (outside this work) into clinical computer systems. JHC is an unpaid director of QResearch, a not-for-profit organisation which is a partnership between the University of Oxford and EMIS Health who supply the QResearch database used for this work. JHC is an NIHR Senior Investigator outside the scope of this work. CC reports grants from NIHR and research councils outside the scope of this work during the past 36 months. All other authors declare no competing interests.Ethical Approval: The QResearch® ethics approval was provided by the East Midlands-Derby Research Ethics Committee[reference 18/EM/0400] and reviewed by the QResearch science committee [Project OX300].