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Over 65s flu vaccination programme was ineffective, data show

BMJ 2017; 358 doi: https://doi.org/10.1136/bmj.j4146 (Published 05 September 2017) Cite this as: BMJ 2017;358:j4146
  1. Nigel Hawkes
  1. London

Last winter’s flu vaccination programme in the over-65s was ineffective, according to new data from Public Health England (PHE).1

Provisional estimates show that for all age groups combined, the vaccine effectiveness against influenza A and B was 39.8% (85% CI 23.1 to 52.8). But for the over-65s, the principal target of the campaign, effectiveness was −6.3% (CI −95.5 to 42.0).

PHE said that the failure of the campaign in older people meant that better vaccines were needed for them. “It is increasingly recognised that the current generation of flu vaccines often work less well in the elderly, likely because of factors such as the weaker immune systems in this population,” a statement said in response to questions from The BMJ. “Nonetheless, over a number of years, flu vaccine generally provides an important level of protection to elderly people.”

The overall effectiveness rate was raised principally by excellent results for children using a live attenuated vaccine, given nasally rather than by injection. This in itself is interesting because this vaccine has been abandoned as ineffective in the US. The PHE figures indicate that effectiveness of the live vaccine in those aged 2 to 17 was 65.8% (CI 30.3% to 83.0%).

The annual campaign vaccinates more than 10 million people at a total cost (not including advertising) to the NHS of more than £160m (€175m; $208m) a year: £6.00 for the vaccine and £9.80 for administering it. PHE’s announcement of its new analysis1 emphasised the positive news about children rather than the failure in the over-65s.

PHE has no plans to change its 2017-18 campaign in the light of the mixed results. “We did not find that the vaccine was significantly effective in protecting against influenza in primary care for the over-65 population last season,” the PHE statement said. “This means that other interventions, such as the use of antiviral therapies and prophylaxis, and tackling spread in the wider community, are important.” Vaccination nevertheless “remains the best protection we have against the influenza virus.”

The success of the live vaccine in children deepens a mystery that has so far baffled flu experts, which is why it works in some places but not others. The US stopped providing the nasal vaccine in 2015-16 after studies showed it to be ineffective.

This move prompted other countries, including Canada and Germany, to alter their own policies, leaving the UK and Finland among only a few countries that continue to use it on a widespread basis. In the UK, vaccinating the young is now seen as the best chance of indirectly protecting their grandparents.

Many attempts have been made to explain the divergent results, including a meta-analysis2 by the vaccine’s manufacturer, Medimmune (part of Astra Zeneca), which concluded that the effectiveness of the vaccine against the H1N1 strain was less than the inactivated vaccine used in adults. Against H3N2 the picture was better but still mixed. “The effectiveness of the live attenuated vaccine has not been consistently demonstrated since the 2009 flu pandemic,” the analysis concluded.

A study by PHE scientists3 showed that the live vaccine does better in years when the H3N2 strain predominates, and the injected vaccine does worse—just as shown in the new PHE data. Why the live vaccine does so poorly against H1N1 remains in question, though one theory is that H1N1 lacks sufficient ability to proliferate in the human host, to which it has only recently adapted. For 2017-18 the World Health Organization has recommended using a different H1N1 strain but it is not known if this will make any difference.

The Joint Committee on Vaccination and Immunisation has recommended continuing the live vaccine programme in children, as has its Finnish equivalent. But unless results against H1N1 pick up, the future of the vaccine could be under threat, the PHE team concludes, because its market is shrinking.

References

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