Since both conditions affect the respiratory system and cause inflammation in the body, symptoms of the two conditions may mimic one another, especially in people already suffering from chronic allergies or asthma, who tend to cough and experience shortness of breath when exposed to the allergens they're sensitive to. 

Still, there are ways to tell the two conditions apart with some certainty, as there are specific symptoms that are different in the two illnesses in question, or such that are more common in one of the conditions, but not the other. As you can tell by taking a look at the visual comparison of common allergy symptoms with common signs of COVID-19 below, one of the main distinctions between the two conditions is the presence of a fever.

Related Article: Covid-19 or the Flu: How to Tell the Difference

The wide majority of COVID-19 patients who exhibit symptoms of the disease report having a high fever for days on end and this fever can be accompanied by a sore throat, fatigue, and muscle pains in the beginning stages of a SARS-CoV-2 infection. After 5 days of having a fever, patients may also start feeling a shortness of breath, wheezing, and other signs of viral pneumonia. Respiratory allergies, on the other hand, are very rarely associated with a fever, so the presence of such can point to an infection rather than an allergic reaction.