nMRCGP Exam Update - Influenza vaccination

Dr Louise Newson is a GP in the West Midlands and author of 'Hot Topics for MRCGP and General Practitioners', PasTest, 2006

Current situation

  • During the winter months there is usually an outbreak of influenza, caused by influenza A or B virus, which results in an increased workload for both primary care teams and hospitals.
  • Influenza causes between 10,500 and 25,000 deaths a year in England and Wales and is responsible for about 800,000 visits to GPs a year.
  • There is plenty of evidence to support the effectiveness of the vaccine; it reduces mortality and morbidity in high-risk groups.

What is the evidence?

  • There is not sufficient evid-ence to recommend universal vaccination against influenza in healthy adults. A review found that vaccinating healthy adults reduced their chances of developing flu-like illness by only a quarter and the number of working days lost by less than half a day (Cochrane Database Syst Rev 2007 2: CD001269).
  • One study has demonstrated that adults with diabetes, like other high-risk groups, benefit from receiving the influenza vaccine each year, regardless of age (Diabetes Care 2006; 29: 1,771-6).
  • A recent observational study found that influenza vaccination was associated with a 27 per cent reduction in the risk of hospitalisation for pneumonia or influenza and a 48 per cent reduction in the risk of death (N Engl J Med 2007; 357: 1,373-81).
  • A study has shown that many older people do not believe themselves to be at risk from influenza (Br J Gen Pract 2007; 57: 352-8). Individual prompts, especially from GPs, seem to be the most significant motivators to attend for immunisation.
  • One study found that the influenza vaccine reduced mortality by about a third when patients were admitted to hospital with community-acquired pneumonia (Arch Intern Med 2007; 167: 53-9).
  • Although there is little evidence to support the cost-effectiveness of the flu vaccination programme, there is still evidence that immunisation reduces pneu-monia, hospital admissions and mortality (BMJ 2006; 333: 1,241).

Implications for practice

  • A systematic review has shown that neuraminidase inhibitors have low effec-tiveness and should not be used in seasonal influenza control.

The authors of the review recommend that these drugs should only be used in a serious epidemic or pandemic, alongside other public health measures (Lancet 2006; 367: 303-13).

  • The possible emergence of resistance further limits the routine use of neuraminidase inhibitors.
  • Although amantadine is licensed for treatment of influenza A, it is no longer recommended (see NICE guidance).

Summary Points

  • Influenza still leads to many deaths in the UK.
  • Vaccine use leads to a reduction in pneumonia and death.
  • Many elderly people underestimate their risk of influenza.
  • Cost-effectiveness of antivirals is still unproven.

Resources

  • NICE guidance: Influenza (prophylaxis), amantadine, oseltamivir and zanamivir (September 2008).
  • Community-based virological surveillance schemes, including those run by the Health Protection Agency.

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