Building immunity

Hey guys! New toddler teacher here wondering how I build more immunity so I’m not constantly getting sick. I wash hands all day and try to practice good healthy habits but I still have the 2 year olds sneezing and coughing in my face every once in a while. I’ve been teaching for 6 months and I feel like I’ve had a running nose the whole time! Any suggestions on how to stay more cleared out would be great! Thanks