Clinical, immunological and virological characterization of COVID 19 patients that test re positive for SARS CoV 2 by RT PCR
Background COVID 19 pandemic is underway. Some COVID 19 cases re tested positive for SARS CoV 2 RNA after discharge raising the public concern on their infectivity. Characterization of re positive cases are urgently needed for designing intervention strategies. Methods Clinical data were obtained through Guangdong COVID 19 surveillance network. Neutralization antibody titre was determined using a microneutralization assay. Potential infectivity of clinical samples was evaluated after the cell inoculation. SARS CoV 2 RNA was detected using three different RT PCR kits and multiplex PCR with nanopore sequencing. Results Among 619 discharged COVID 19 cases, 87 were re tested as SARS CoV 2 positive in circumstance of social isolation. All re positive cases had mild or moderate symptoms in initial diagnosis and a younger age distribution (mean, 30.4) Re positive cases (n=59) exhibited similar neutralization antibodies (NAbs) titre distributions to other COVID 19 cases (n=150) parallel tested in this study. No infective viral strain could be obtained by culture and none full length viral genomes could be sequenced for all re positive cases. Conclusions Re positive SARS CoV 2 was not caused by the secondary infection and was identified in around 14% of discharged cases. A robust Nabs response and a potential virus genome degradation were detected from nearly all re positive cases suggesting a lower transmission risk, especially through a respiratory route.
medRxiv