Table 1.

Key points for differentiating COVID-19 from CMV pneumonia or Pneumocystis jirovecii pneumonia.

Diseases	Susceptible patients	Manifestations	Laboratory tests	CT findings	Pharmaceutical treatment
COVID-19	All recipients are susceptible, but the elderly with underlying disease, such as cancer, diabetes, or cardiovascular disease, may be more susceptible	No or slight fever, dry cough, fatigue, and widespread skeletal muscle aching	A slight decrease in white blood cell and moderate decrease in lymphocyte counts; increased levels of serum myocardial and liver enzymes, such as LDH and ALT	The manifestations are varied; scattered ground-glass and multiple consolidation opacities in single or bilateral lungs, which are prominent in the middle and outer zones of the lung	No specific effective drugs at the moment
CMV pneumonia	Serum CMV-IgG is the main determinant, with donor+ and recipient- being a highly significant risk factor for the recipient	Fever, mild to high fever, dry cough, fatigue, chest tightness and shortness of breath	A moderate decrease in white blood cells; in most cases, no significant increase in serum levels of myocardial or liver enzymes	Diffused ground-glass opacities in the double lungs in the early stage, and interstitial fibrosis appear in the late or chronic stage, rare to have a big consolidation	Ganciclovir, Val-ganciclovir, foscarnet sodium, cidofovir
Pneumocystis jirovecii pneumonia	Patients with severe immunosuppression, especially with CD4+ lymphocytes decrease or deficiency	Fever, dry cough, dyspnea, chest tightness, severe hypoxemia	Severe decrease in lymphocyte counts; CD4+ lymphocytes are always less than 200/L, serum G test (+), LDH always increased; trophozoites and cysts can be found in BALF	Diffused ground-glass opacities in the upper lungs with slight interstitial fibrosis in the lower lungs, rare to have consolidation	Compound sulfamethoxazole, pentamidine, clindamycin, caspofungin

CMV: cytomegalovirus; COVID-19: novel coronavirus disease; LDH: lactate dehydrogenase; ALT: alanine-aminotransferase; BALF: bronchoalveolar lavage fluid.