A ‘period of incapacity for work’ (PIW) is any day or days in which you are incapable of doing the job you are employed to do because of sickness or disability. Weekends and public holidays count – therefore, every day of the week can count towards a PIW, including days when you would not have worked even if you had been fit. PIWs separated by eight weeks or less are linked and count as one PIW.
SSCBA, S.152

There are some situations when you will qualify even if you are not actually sick on a particular day. You can be treated as incapable of work for days when you are under medical care for some specific disease or bodily or mental disablement and a doctor has advised you not to work for precautionary or convalescent reasons, provided you do not work on those days. You are also treated as incapable of work if you are prevented from working (having received the due notice in writing) because you have, are suspected of having or have been in contact