Many jobs involve close interactions between employees and customers. While these jobs are incredibly rewarding for many people, they also expose you to countless people, each of whom could get you sick. The simple math of the situation dictates that you will likely get sick from a customer, no matter how careful you are. You will run across a person that has poor hygiene habits or doesn't cover their mouth when they cough, eventually you will get sick. Thus, the issue is, if you get sick, is your employer responsible? And, more importantly, are you entitled to workers' compensation?
Ideally, you are entitled to workers' compensation whenever you catch an illness or get injured while at work. Thus, even common colds and the flu are covered. But, the evidentiary reality is that, if your claim is challenged, it might be difficult to substantiate that you got sick while working and not on your own time. Furthermore, keep in mind that some states do not provide worker protection for common illnesses, like colds and the flu.
But, workers' compensation isn't your only avenue for recovery. You can also file a lawsuit for damages if your employer was negligent in forcing you into contact with sick customers or failed to provide you adequate protection (imagine nurses who aren't given face masks).
If you were unable to work because you caught an illness while on the job, then you may want to call a lawyer to discuss your compensation options. Most things, like a simple cold, are easily excusable. But if you incur a serious Workplace Illness that leaves you bedridden for a week or more, you may need the assistance of an attorney to file a claim and protect your job. You don't need to lose your job or accept reduced pay if you get sick from your work; you may be entitled to compensation to make up the difference.