This is pure OCD,you are over fearing about infection,bacterial infection is a simple thing
evey one get it , OCD make these kind of small things huge and waste our time on it

-take 15-30 min outdoor or our of your house / meet with friend
-take deep breath it will calm down your mind
-first convince your mind " this is a useless thought"
but OCD will repeat this thought try to ignore

do your work /study

Im ESL