Have you noticed nowadays when you are off sick, you still get phone calls from work? They can be about trivial stuff like someone not being able to find a file, or more important questions that it seems only you know the answer to.
Workers are even asked about who could cover for them, like that's part of your job description. This can come from your boss or supervisor or from fellow workers left in the lurch by the mismanagement above them.
Increasingly, it seems to be alright to harass people at home who are sick. This only increases the anxiety felt by those off sick and sometimes can be used to pressure them to return to work before they should do.
With mobile phones and email it is even harder to escape from intrusive communications from work. Not long ago, you reported sick and sent a sick note. You were only expected to contact your employer to either to send in a renewed sick note or tell them when you'd be back. Nowadays, the employers seem to need daily updates and information that only you can provide.
Sick harassment has spread like a disease spread from middle management who have already sold their soul to the company devil, and seem to expect everyone else to feel ‘loyalty' from their sick bed.
There is no specific legalisation covering being contacted when off sick. If it gets really bad, you could go through a claim for harassment but realistically, how far do you think you would get? So, until the scourge passes, don't encourage them. When you're off sick, screen your calls, ignore the emails and don't be tempted to contact work unless you really have to. It's the only way to stay healthy when you're off sick.