Patients with suspected COVID-19 present to hospital with symptoms of fever, breathlessness, cough, and lethargy, and there are lots of differential diagnoses that should be considered, including:
Community acquired pneumonia
Patients also presents with fever, cough and breathlessness. They will also have infiltrates on the chest x-ray, and should be treated with concurrent antibiotics until COVID-19 infection is confirmed by the throat swab, and blood tests which will help to distinguish between bacterial and viral infection.
Infection in Immunocompromised patients
Any patients with HIV infection, or on long-term steroids or other immunosuppressants, or recent chemotherapy can present with breathlessness, fever and cough, and should be considered for opportunistic infections such as pneumocystis pneumonia, cytomegalovirus and fungal infections.
Recent foreign travel
Consider one of the many causes of fever in someone with history of recent foreign travel, including malaria and typhoid.
Patients with PE also present with breathlessness and hypoxaemia, which may be disproportionate to the degree of infiltrates on the chest radiograph.