Sick on vacation: How employees have to behave to get their days back. If you have a certificate, the days in which you can prove that you were unable to work will be credited to your vacation account.
You are not allowed to extend your vacation on your own and make up for the days that were lost due to illness. Under certain circumstances, health insurance for travel abroad can make sense, as statutory health insurance only covers treatment costs abroad to a limited extent. Possible return transport will not be covered.