Diyyah

Assalamoalaikum dear respected scholars, My Question Is:a person is sick, but still goes to work (Critical Care Unit in hospital). He knows he is somewhat sick, but still goes to work [ He does not realize the potential harm he could be doing to the vulnerable ICU patients by going to work with that sickness ]. In the extreme case that someone or some people die from a sickness unintentionally passed on by this worker, is this worker considered a killer in Islam? Or would this be considered killing by accident? Would there be any expiation for this?Thanks for helping

Hi, I am contacting you in reference of http://www.answering-christianity.com/I have a matter over here. Few months before i had a major car accident and 2 people died in the accident where as i survived. Thinking about the accident i somehow think that i was not concentrating while driving which caused the accident. This matter has been taken in court but no one has been able to contact the family members of those people. I totally have no idea what should now be done since islam states DIYA must be paid since i didn't killed anyone in fight, didn't even had any relation with them and didn't even know them.But still im really concerned what will this case be treated as on the day of judgement since its really disturbing me alot that in my life i tried to do nothing bad but this one event can change my paths from heaven to hell.