Caution: The clinical characteristics of COVID-19 patients at admission are changing

BackgroundWith the emergence of 4rd generation transmission, the prevention and treatment of the novel coronavirus disease 2019 (COVID-19) has entered a new period. We aimed to report several changes in the clinical characteristics at admission of patients with COVID-19. MethodsClinical records and laboratory results of patients suffering from COVID-19 were retrospectively reviewed and matched with the admission dates to analyze the changes in characteristics at the onset of illness. ResultsOf the 89 affected patients, 31 [34.8%] patients were admitted from January 16 to 22, and 58 [65.2%] were admitted from January 23 to 29. Patients were admitted with more systemic symptoms, such as fever (21 [67.7%] of 31), fatigue (13 [41.9%] of 31), and myalgia (7 [22.6%] of 31), before January 23. More patients (10 [32.3%] of 31) admitted before January 23 had a small amount of sputum production compared with a smaller proportion (4 [6.9%] of 58) of the patients admitted after January 23. Other symptoms, such as cough, nausea, diarrhea, and chest tightness, were not significantly different between the two groups. In addition, the group admitted before January 23 had a larger proportion of patients with reduced lymphocyte (13 [54.2%] of 24), CD3 (11 [54.4%] of 21), and CD8 (9 [42.9%] of 21) counts and elevated serum amyloid A (SAA, 18 [75%] of 24). ConclusionsThe initial symptoms of recently infected patients seem more insidious, indicating that the new coronavirus may gradually evolve into a virus similar to influenza and latent in asymptomatic carriers for a long time. SummaryCompared with the cases admitted earlier, more hidden initial symptoms and improved immune system disorders appeared in COVID-19 patients infected recently.