Nucleic acid and antibody assay results in Chinese patients with coronavirus disease 2019 (COVID-19).

Aim: To evaluate the nucleic acid and antibody test results of patients with Coronavirus Disease 2019 (COVID-19) in China.

Methods: All patients with laboratory-confirmed SARS-CoV-2 infection from Jan to Apr 2020were retrospectively analyzed. Clinical characteristics and laboratory test results were obtained from electronic medical records. Patients were divided into three groups based on antibody production, and compared for laboratory test results.

Results: Of 73 patients aged11-82 years, 12 (16.4%), 28 (38.4%), 25 (34.2%) and 8 (11.0%)were ≤ 30, 31-50, 51-70,and ≥ 71 years old, respectively. Thirty-four (46.6%) patients were male. Most individuals had mild symptoms, and no patient died during treatment. All patients were tested positive for SARS-CoV-2 in sputum and nasopharyngeal samples, and 40 (54.8%) were also tested positive in stool. Nine(12.3%) patients were re-positivefor SARS-CoV-2, as assessed by Reverse Transcription-Polymerase Chain Reaction (RT-PCR) after discharge. Sixty-five (89.0%) patients had IgM or IgG antibodies against SARS-CoV-2.Among the four age groups, there was no difference in IgG antibody production (P = 0.664).CD3, CD4, CD8 and CD19 cell counts between the antibody producing and non-producing groups showed no significant differences (all P > 0.05).The antibodies disappeared within two months in four patients. Lymphocyte count, C-reactive protein, IL-6, lactate dehydrogenase, alanine aminotransferase, creatinine and D-Dimer levels were similar in the three groups (all P > 0.05).

Conclusions: Patients after recovery from COVID-19 can be tested positive for SARS-CoV-2.Some patients may produce antibodies only for a short time, or even no antibodies at all.