A study from CaHRU, ‘Influenza vaccination and risk of stroke: self-controlled case-series study‘, recently published in the journal Vaccine, received international coverage in news media. The study of almost 18,000 patients with stroke looked at data from general practices in England using a self-controlled case series analysis, and showed that the risk of suffering a stroke is significantly reduced for up to two months after receiving a flu vaccine.
The lead author was Dr Zahid Asghar, who conducted the research together with Prof Niro Siriwardena (both from CaHRU) and Dr Carol Coupland (from Nottingham University School of Community Health Sciences). This is the fourth in a series of studies over the past 10 years looking at the link between flu vaccination and reduction in risk of heart attack and stroke.
The coverage included articles in The Times, Sun and Scottish Sun newspapers, BBC television and radio and online media outlets in the US, Middle East, Asia, Australasia and South America. The team are now designing future studies to explore the potential for flu vaccination to reduce risk of heart attack and stroke.
Dr Zahid Asghar recently attended the North American Primary Care Research Group (NAPCRG) conference in New York City to present findings from ‘Influenza vaccination and risk of stroke: self-controlled case-series study’. This was an observational study of investigating the association between influenza vaccination and stroke led by Professor Niro Siriwardena, director of CaHRU, and Dr Carol Coupland, associate professor in statistics at the University of Nottingham.
The study involved analysis of almost 18 thousand cases of stroke over a period of eight years from a general practice database, the Clinical Practice Research Datalink. The investigators found a significant reduction in risk of stroke up to 59 days following vaccination. The work follows publication of a case-control study earlier this year and involving almost 10,000 patients showing a 20% reduction in risk of stroke associated with flu vaccination together with previous studies conducted by Professor Siriwardena and his team showing a reduction in risk of heart attack associated with influenza vaccine.
It is not known how influenza vaccination prevents heart attack or stroke. It might be because influenza has been shown to occur two to four weeks before these conditions and may trigger them in a proportion of cases or it might be due to immunological protection from the vaccine. There was worldwide interest in this area of research following the team’s study published in the Canadian Medical Association Journal.
A further study, published in the Journal of Infectious Diseases, points to a link between influenza as a trigger of cardiovascular events, while presentations given in the past week in Toronto suggest that influenza vaccination might prevent such events.
Members of the Community and Health Research Unit from the University of Lincoln recently attended the combined Society of Academic Primary Care and RCGP Annual Scientific Meeting in Glasgow where they were selected to give five oral presentations on some of the team’s current research into cardiovascular disease, adult vaccination and insomnia treatment. The conference provided a wonderful opportunity for junior and senior members of the team to present work at an international conference.
The study was funded by the NIHR Policy Research Programme to determine how to improve flu vaccination rates in at-risk groups in the UK. Flu vaccine uptake is below the national and international target of 75% particularly in the under 65-year-old age group. This study used an online survey to GPs, nurses and practice managers to identify which strategies and procedures reported were associated with higher rates of flu vaccine uptake. The recommendations have been summarised in annual guidance in the seasonal flu plan (Annex B – GP practice checklist p11-12) from the UK Chief Medical Officer, Dame Professor Sally Davies.
The study builds on previous work led by Niro Siriwardena on methods to improve influenza and pneumococcal vaccination rates in primary care and in general practice in Lincolnshire which led to a definitive cluster randomised controlled study of an educational intervention for general practice. The Community and Health Research Group are also working on the role of influenza vaccination in preventing cardiovascular disease. After studies showing a reduction in risk of heart attack linked to influenza vaccination (published in the Canadian Medical Association Journal and Vaccine) the team are now working on a case-control study to investigate potential role for influenza and/or pneumococcal vaccination in prevention against stroke and transient ischaemic attack (IPVASTIA), funded by the NIHR Research for Patient Benefit programme.
The new study in BMJ Open has identified seven key strategies that were significantly associated with the success of practices’ seasonal flu vaccination campaigns which include leadership (a named responsible flu lead), ordering sufficient vaccines, up-to-date registers of patients at risk, starting the programme early, robust call and recall arrangements, offering appointments and opportunistically vaccination, and working with community midwives for vaccination in pregnancy. If widely implemented by general practices, these strategies could improve vaccination rates by 7% to 8%. The learning has been publicised in professional magazines and translated into an online learning module for GPs which is having impact on professional practice.