It’s easy to become complacent about flu, especially during nonpandemic years. Yet PHE estimates that it caused 16,415 extra deaths during the 2014/15 season in England and Wales.1 That is more than the annual mortality from breast (11,716 in 2012) or prostate (10,837) cancer. Recent studies confirm that vaccination is clinically and cost effective, with benefits extending beyond the respiratory tract.
Apart from pneumonia, flu can contribute to heart failure, and increasing evidence suggests that it can trigger strokes. A systematic review of 12 studies found that respiratory infections within the previous week or month tripled or doubled the risk of ischaemic stroke respectively (odds ratio [OR] 2.91 and 2.41 respectively).3 Such findings raise the prospect that flu jabs could protect against stroke. Previous studies showed conflicting results.2
Against this background, researchers from the University of Lincoln examined the records of 17,853 stroke patients who received at least one flu jab. The researchers compared the number of strokes up to 180 days after immunisation with a baseline when the patients were unprotected.2 In general, about 59% of recipients show protective levels of antibodies within one week of vaccination.4 Compared to baseline, stroke risk fell by 36% 4-7 days after vaccination, by 30% at 8-14 days, 24% at 15–28 days and 17% at 29-59 days.2
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