Seasonal allergies and COVID-19 are caused by different things. While some symptoms of COVID may be similar to seasonal allergy symptoms, COVID is a viral infection that typically includes more symptoms. A doctor can test for COVID to rule it out, or you can use at-home COVID testing. It is also possible for the flu or a cold to cause allergy-like symptoms. If fever, diarrhea, or body aches are present, it is likely an infection, because seasonal allergies do not cause these symptoms.