England’s chief medical officer Sir Liam Donaldson can sound gloomy and pessimistic but he sounded very upbeat in this week’s swine flu update, saying: “We may have got a lucky break in how the virus has behaved at the start of our flu season and we may be able to get the vaccine out there before our flu season really gets under way. I’m looking at it very optimistically.”
Last week GP consultation rates with flu-like illness rose slightly from 22.2 to 26.3 per 100,000, still well below the threshold for normal seasonal flu activity. Use of the National Pandemic Flu Service is on the rise too. Although the Health Protection Agency’s (HPA) weekly flu report doesn’t state the total number of people using sneeze and click, they do give some percentages: use has increased by 12%, less than the 39% rise the week before.
Why the flu vaccine is less effective than everyone thinks
The incidence of seasonal influenza during the autumn and winter months is less that 1% according to an editorial by Tom Jefferson in BMJ Clinical Evidence. This figure comes from evidence from prospective studies of seasonal influenza and influenza-like illness (ILI). He writes: “…evidence presented here points to influenza being a relatively rare cause of ILI and a relatively rare disease. It follows that vaccines may not be appropriate preventive interventions for either influenza or ILI.”
As the pie chart below shows, only a small proportion (just over 10%) of influenza like illnesses can be attributed to influenza viruses. With incidence of influenza being so low, any influenza vaccine will have little impact on the incidence of influenza-like illness.
How do the conclusions reached by Jefferson affect the swine flu vaccine? According to the HPA the proportion of patients with influenza-like illness testing positive for influenza has fluctuated between around 10 and 30%. If these levels accurately reflect the broader population and remain low, perhaps the new swine flu vaccine won’t have as big an impact as many are hoping for.
Incidence of influenza-like illnesses (ILI) per 10,000 people (calculated from prospective studies), with breakdown by agent, based on information in pie studies.
Are you qualified to vaccinate?
How hard can it be to administer a vaccine? Nurses in Somerset have been asked to attend a day’s training before the vaccination programme begins according to a member of the social networking site doc2doc. Members of the website are unimpressed:
“It comes in a multi-dose vial, as opposed to the regular flu vaccine. You can’t expect nurses with four years of training, post-training qualifications in practice nursing and years of experience to be able to give a vaccine out of a multi-dose vial without a day’s dedicated training. Obviously.”
Do you feel competent to administer a multi-dose vaccine? Are you in need of swine support? Share your worries here.
Tom Nolan is a GP trainee, London.