Our sickness policy says two episodes of sickness in a rolling 12 month period. An episode of sick can be anything from 1 day to 6 months so if someone feels unwell they invariably take at least a week when they perhaps need a couple of days off.
Our biggest causes of sickness absence are stress but we are not allowed to ask the cause, and muscular skeletal which can range from minor joint pain to major surgery.
Our employers had a problematic sickness policy that meant that people like me who were part time nurses on long shifts (of which there were many being a hospital) could only have two days off sick per year before it triggered the absence management disciplinary procedure.
They changed it a few years back, but not before many people had been threatened with dismissal for having as little as four days off in a two year period, and the trust had spent a fortune on the expensive sickness absence management meetings that had to be attended by managers, senior HR reps and union reps and also on expensive unnecessary referrals to occupational health. At one point the majority of the part time nurses in my department were somewhere on the disciplinary continuum.
We now have a legacy of people too scared to take time off work when they're ill, which means yes, they come to work and infect everyone els, patients included.