BBC: New data suggests that a minimum of two and a half hours of vigorous exercise per week decreases the chance of developing influenza.
The researchers say their findings suggest 100 cases of flu per 1,000 people could be prevented just by engaging in vigorous exercise.
They also said this year's survey found some of the lowest reports of flu-like illness in recent years.
Over the winter flu season, only 4.7% of reports were positive for flu-like symptoms compared with 6% last year.
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