The facts are:
People get sick- cover is needed. The schools are putting cover in place in a good way (via supply teachers and assistants).
There is a process for dealing with persistent sickness that is not genuine e.g. Long term- Bradford Scale.
This situation is not exclusive to Schools or the CS. It's a factor in all businesses and it costs money. You have to budget for it accordingly.
The teaching profession is getting more and more difficult due to ill discipline by parents, causing disruption in schools and added stress for teachers. This could contribute to worsening sickness absence.