Clinical and immunological characteristics of coronavirus disease 2019 patients with redetectable viral RNA post-discharge during the quarantine period

Coronavirus disease 2019 (COVID-19) caused by the novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) continues to spread worldwide. The global pandemic poses a serious challenge to the medical community. Detection of serum immunoglobulin G (IgG) and immunoglobulin M (IgM) is crucial for the diagnosis of COVID-19. IgG is particularly important for antiviral response assessment. Our study divided 51 patients into "persistence" and "non-persistence" groups according to the status of positive RNA, and the clinical and immunological characteristics of two groups of patients with redetectable viral RNA post-discharge during their quarantine period were studied, including the clinical signs, symptoms, hospitalization time and laboratory blood routine tests, biochemical indexes, and IgM/IgG antibodies titers detecting. Overall, the median age was 57.0 (21–90) years, and the median time was 9 days from discharge to redetectable viral RNA. The median titers of IgM and IgG antibodies were 23.19 AU/mL and 170.36 AU/mL (P>0.05), respectively. The median ratio of IgG/IgM was 6.63 and the median ratio of IgG/IgM was 8.02 and 4.03 for persistence and non-persistence groups, respectively (P=0.079). The median length of hospital stays for patients that had reached the composite endpoint was 16.5 and 9 days in the persistence and non-persistence groups. In conclusion, there was a significant difference in hospitalization time between the two groups of patients, but there was no statistical difference in the IgM/IgG titer detection, which required more data to verify.