Employer’s policy is to write up employees who have to leave sick?

Is this legal? My employer operates on a three strike policy. I had to go home early today because I feel like I have the flu, and they told me that they can't say yes or no but that if I leave I'll be written up per policy. This is barbaric to me. We are still in a global pandemic and I'm being written up for having to leave with the potential flu? I'm in the United States, Oregon specifically.