Background: Even since the end of 2019, a small virus termed as SARS-CoV-2 has been making big impact on global people’s health. Despite the clinical features of thousands COVID patients have been reported, the underlying immunity and early biomarkers have not been documented. Methods: Medical records, laboratory results and chest CT scans were retrospectively collected for 13 patients diagnosed as COVID-19, in Baoji Centre Hospital, Shaanxi Province, China, from Jan 28 to Feb 24. Dynamic observations and analyses were performed, using demographic data, the serum biochemistry profile, chest CT imaging of 12 amongst 13 COVID patients Findings: The average age of patients was 48·33 years (range, 27 to 71 years). There were 10 patients complaining of cough (76·92%), 9 patients complaining of cough (69·23%), 2 patients with diarrhea (15·38%), 2 cases with expectoration (15·38%), 1 case reporting short of breath (7·69%). Six cases had comorbidities. All 12 patients had SAA tests at multiple time-points (except 1 critical type transmitted), with higher expression of SAA in severe cases compared with common type of cases ( P <0·01). Typical CT findings were ground glass opacity within 3-5 days following admission. Re-examinations revealed that the number of lesions decreased, part of the range was reduced, mainly solid shadows, part of the density increased with grid shadows. All 12 patients were discharged following successful treatment. Interpretation: By dynamic observations of the serum biochemistry profile, chest CT imaging of 12 amongst 13 COVID patients outside Wuhan, SAA was identified as a potential biomarker linked with clinical severity. Moreover, immune cell sorting analysis unraveled the landscape of innate and adaptive immunity machinery underlying COVID-19.Funding Statement: No funding was received for the study.Declaration of Interests: All authors declare no competing interests.Ethics Approval Statement: The study was approved by the Ethics Committee of Baoji Municipal Central Hospital (Approval number: BZYL2020-2). Given the emergency with public health threatening risks, informed consent requirements were waived.