for vomiting bugs - keep them of school for 48 hours at least.
for colds/flu - please keep them off until you feel they all well to resume a full day's work. This is especially paramount at present, due to the strain of cold/flu about. This prevents the spread to others. Also encourage them to wash their hands frequently.
A reminder that if a child is on an antibiotic, they should be able to have it administered outside school hours or a parent/guardian can call during break/lunchtime to administer it. No member of staff should have to do this. Our policy is for the administering of calpol/paracetamol only