Margaret McCartney: What use is mass flu vaccination?

It’s flu vaccination season again. People over 65 and those aged six months to 65 years who have a clinical risk factor (such as heart disease, asthma with regular inhaled steroid use, or chronic kidney disease) are eligible for the vaccine, along with people who live in residential care homes, pregnant women, and carers. Health and social care workers in direct contact with patients are also being encouraged to have the vaccine. But does it work?^{1 2 3 4}

For each healthy adult, a Cochrane review found that vaccination saved an average of just 0.04 days off work and concluded that no evidence supported it as a routine public health measure.⁵ And among over 65s, Cochrane reviews found only poor quality data and were unable to draw conclusions of any benefit, thus recommending more trials.⁶ As for children, Cochrane again found the available studies to be of poor quality: the number needed to vaccinate to prevent one case ranged from seven (live vaccine) to 28 (inactivated vaccine),⁷ and effectiveness varied greatly depending on the season.⁸

The evidence is uncertain among people with asthma⁹; however, flu vaccination does seem to usefully reduce exacerbations in people who have chronic obstructive pulmonary disease.¹⁰ And a review of flu vaccination trials for healthcare workers who looked after older people in long term residential care found no meaningful difference in the number of cases of laboratory confirmed flu, admissions to hospital, or deaths from respiratory infections in residents.¹¹

So, why are we vaccinating so many people in whom we have no proof that it works? We should surely be doing randomised controlled trials of the vaccine in healthy over 65s and healthcare workers, at least.

The NHS has a “Flu Fighter” campaign to encourage uptake and offer incentives for staff to bare their biceps. In return for vaccination, hospitals have offered their staff entry into cash prize draws, as well as chocolates, lollipops, cakes, biscuits, stickers that read “I’m a Flu Fighter,” and even an extra day’s annual leave, some freedom of information requests have shown. But will those days off work be offset by the average 0.04 days saved through vaccination?

Treating children is one thing; treating adults like children is quite another. The Department of Health wants trusts to achieve a 75% uptake in flu vaccination for staff,¹ when it would be better off ensuring that resources are used where they can do some good. I would have the vaccination if a high quality trial showed that it was worth it for me or my patients. But flu vaccination is offered millions of times every year at huge opportunity cost; given so much uncertainty, this policy is impossible to justify.

Cite this as: BMJ 2014;349:g6182