Should healthcare workers have the swine flu vaccine?BMJ 2009; 339 doi: http://dx.doi.org/10.1136/bmj.b3398 (Published 26 August 2009) Cite this as: BMJ 2009;339:b3398
- 1Unit of Public Health, Epidemiology and Biostatistics, Public Health Building, University of Birmingham, Edgbaston, Birmingham B15 2TT
- 2University College of London Centre for Infectious Disease Epidemiology, Department of Infection and Population Health, Royal Free Campus, London NW3 2PF
The first batch of vaccine for the influenza A/H1N1 2009 “swine flu” pandemic should be ready and licensed by October,1 and the United Kingdom’s government has ordered enough vaccine for each person to receive two doses. Because vaccine production will take several months to complete, a prioritisation plan has just been announced, and frontline healthcare workers will be among the first to be offered vaccination. The potential benefits of influenza vaccination for healthcare workers are threefold—personal protection, protection of patients, and reduction of absenteeism. There is good evidence that among healthcare workers a well matched seasonal vaccine is 85-90% effective in preventing serologically confirmed influenza,2 that it indirectly protects elderly patients in some settings,3 that it may reduce absenteeism, and that it has limited and mild adverse effects.4 Despite this, uptake of seasonal flu vaccine among healthcare workers has consistently been low (in winter 2008-9 only 16.5% of healthcare workers in England received the vaccine).5 So will uptake be any different during a pandemic?
More than 75% of healthcare workers responding to a survey in Leicester, UK, indicated willingness to accept a pandemic vaccine.6 However, this survey was conducted when the main pandemic risk appeared to be H5N1, which is associated with a high case fatality rate, rather than the current H1N1 strain, which is associated with relatively low mortality. In the linked study (doi:10.1136/bmj.b3391), Chor and colleagues show that, in a sample of 2255 healthcare workers in Hong Kong hospitals, the intention to accept pre-pandemic vaccines increased from 28.4% for H5N1 vaccine during the World Health Organization alert phase 3 to 47.9% for H1N1 at phase 5.7 An online poll just conducted by the Nursing Times reports that 37% of frontline nurses who replied were currently planning to be vaccinated, 33% were undecided, but 30% were not planning to be vaccinated. In line with surveys of seasonal flu vaccine uptake, intended acceptance of pre-pandemic or pandemic flu vaccines was associated with receipt of previous seasonal flu vaccines, perceived likelihood of being infected, and belief in the efficacy of flu vaccines.6 7 Reasons for refusing the vaccine included concerns about safety and efficacy, and low perceived threat of a pandemic.
Can we be sure that the new pandemic H1N1 vaccine will be as effective and safe as seasonal flu vaccines? The European Commission has already approved four “mock-up” vaccines developed by Baxter, GlaxoSmithKline, and Novartis on the basis of earlier immunogenicity and safety data generated with H5N1 virus strains. These mock-ups were developed knowing that the virus strain would be different in the event of a pandemic, and altogether they have been tested in more than 8000 people. The European Medicines Agency states that “decades of experience with seasonal influenza vaccines indicate that insertion of a new strain in a vaccine, as will apply with the change from H5N1 to H1N1 in the mock-up vaccines, should not substantially affect the safety or level of protection offered.”8 Two doses of an adjuvanted H5N1 vaccine have been shown to reach the licensing criteria for immunogenicity while maintaining an antigen sparing approach and to be cross protective across different clades of H5N1.9 Trials to evaluate immunogenicity and safety with the new H1N1 antigen inserted in the mock-up vaccines are currently under way, and these results will inform licensing decisions.
A particular concern for recipients may be the association of the 1976-7 swine flu vaccine with Guillain-Barré syndrome, with an attributable risk of around 12 cases per million vaccinations.10 This rare event has decreased greatly during the past 15 years (to around 0.7 reports/million vaccinations).11 Indeed, recent research suggests no significant increase in the risk of this syndrome after vaccination, but a greater risk after natural influenza infection. Thus, even if the vaccine were associated with a small increase in the risk of the syndrome, this would probably be outweighed by a protective effect against flu related Guillain-Barré syndrome.12 However, as with all new drugs, post-marketing surveillance (including for Guillain-Barré syndrome) is the only way to identify rare adverse events.
Healthcare workers in England are being urged to be vaccinated against pandemic and seasonal flu as soon as possible to protect themselves and their patients.1 NHS chief executives are also being directed to ensure maximum uptake. Implementation of the pandemic flu vaccination programme should take on board the lessons learnt from research on vaccination for seasonal flu—simple education and promotion and onsite clinics have not achieved high vaccination rates, but the additional use of convenient mobile systems, monitoring and feedback systems, and “opt-out” systems (where healthcare workers need to indicate their reasons for not accepting the vaccine) show promise.
In a pandemic there are many uncertainties, but without vaccination many healthcare workers will become infected. Although this will be a mild illness for most, deaths in previously healthy young adults have occurred. Flu vaccination is likely to reduce this risk and has a well understood safety profile. Vaccination may also help to keep the healthcare system operating at maximum capacity throughout the pandemic.
Cite this as: BMJ 2009;339:b3398
Competing interests: AH was invited to speak at a Sanofi symposium on influenza vaccination of healthcare workers in Brussels in 2009. Travel expenses, but no fee, were paid.
Provenance and peer review: Commissioned; not externally peer reviewed.