There are several factors to consider.
Many symptoms are associated with long COVID‑19. As mentioned earlier, some of these symptoms are common with other diseases.
You really have to assess the whole patient. You have to look at their medical situation before and after the infection. In order to make a diagnosis, you have to understand how that person's condition has evolved. At the moment, it's difficult to make a diagnosis, and that's a problem. The patient must have at least one symptom that persists for two months. However, symptoms can fluctuate over time and can even occur after recovery. They may occur after a month or three months, depending on the definition used.
Diagnosis is complicated for physicians who are unfamiliar with the symptoms and the tools that can help them assess some of the less obvious symptoms. Diagnoses such as postural orthostatic tachycardia syndrome, which has already been mentioned, require expertise.
When physicians don't necessarily have that expertise, we need to find ways to equip them. Otherwise, they need to be told what resources they can refer their patients to and where those patients can really be assessed in their entirety.