Clinical, immunological and virological characterization of COVID-19 patients that test re-positive for SARS-CoV-2 by RT-PCR

Abstract

Background Some COVID-19 cases test positive again for SARS-CoV-2 RNA following negative test results and discharge, raising questions about the meaning of virus detection. Better characterization of re-positive cases is urgently needed. Methods Clinical data were obtained through Guangdong's COVID-19 surveillance network. Neutralization antibody titre was determined using microneutralization assays. Potential infectivity of clinical samples was evaluated by cell inoculation. SARS-CoV-2 RNA was detected using three different RT-PCR kits and multiplex PCR with nanopore sequencing. Findings Among 619 discharged COVID-19 cases, 87 re-tested as SARS-CoV-2 positive in circumstances of social isolation. All re-positive cases had mild or moderate symptoms at initial diagnosis and were younger on average (median, 28). Re -positive cases ( n = 59) exhibited similar neutralization antibodies (NAbs) titre distributions to other COVID-19 cases ( n = 218) tested here. No infectious strain could be obtained by culture and no full-length viral genomes could be sequenced from re-positive cases. Interpretation Re -positive SARS-CoV-2 cases do not appear to be caused by active reinfection and were identified in ~14% of discharged cases. A robust NAb response and potential virus genome degradation were detected in almost all re-positive cases, suggesting a substantially lower transmission risk, especially through respiratory routes.

A systematic review on the recurrence of SARS-CoV-2 virus: frequency, risk factors, and possible explanations

“…As an exception, a cohort study on paediatrics reported that seven patients out of 14 (50%) experienced recurrence [ 20 ]. Regardless of study type, based on 57 studies with available data (1019 patients), the first detection of recurrence of SARS-CoV-2 had been reported within a mean of 20 days, with a range of 1–140 days after meeting criteria for discharge [ 3 , 13 , 15–17 , 19–23 , 26–33 , 35–39 , 41–74 ].…”

“…Within the first admission, considering 1064 patients, the majority of re-positive cases ( n = 987; 92.7%) were asymptomatic or had mild to moderate symptoms [ 1 , 3 , 13 , 14 , 16 , 17 , 19 , 21–24 , 26–28 , 30–33 , 36–45 , 47 , 48 , 50–52 , 54 , 56 , 58 , 59 , 61 , 62 , 64–67 , 69–73 , 75 , 77 ], but some of them had severe or critical disease ( n = 77, 7.3%) [ 1 , 13 , 18 , 21 , 23 , 24 , 27 , 30 , 31 , 35 , 36 , 39 , 42 , 43 , 46 , 49 , 55 , 60 , 63 , 68 , 74 ]. To compare the severity of disease during the first and second courses of illness in re-positive patients, 57 studies including 858 re-positive patients, it was reported that the disease severity decreased or remained unchanged in 835 cases (97.3%) [ 13 , 15–20 , 23 , 24 , 26 , 28–31 , 33 , 36–48 , 50 , 52–54 , 58–61 , 65–68 , 70 , 71 , …”

“…Meanwhile, 39 studies reported concerning temporal changes in the manifestations of chest CT scans of 375 re-positive patients. Among them, 290 and 65 cases presented improved [ 17 , 18 , 20 , 23 , 26 , 28–31 , 36 , 38 , 43 , 47 , 50 , 52–54 , 58–61 , 67 ] and unchanged lesions [ 17 , 23 , 30 , 40 , 48 ], respectively. Also, CT worsening was observed in 20 patients [ 18 , 19 , 32 , 35 , 39 , 46 , 49 , 51 , 55 , 57 , 62 , 63 , 69 , 72 ].…”

SARS-CoV-2 RNA reverse-transcribed and integrated into the human genome

“…Although bona fide re-infection of SARS-CoV-2 after recovery has been reported lately 15 , cohort-based studies with strict quarantine on subjects recovered from COVID-19 suggested "re-positive" cases were not caused by re-infection 16,17 . Furthermore, no replication-competent virus was isolated or spread from these PCR-positive patients 1-3, 5,6,12 . The cause for such prolonged and recurrent viral RNA production is unknown.…”

Current methods and prospects of coronavirus detection

“…The specificity and sensitivity of RT-qPCR were 98.08% and 100.0%, respectively [ 74 ]. In addition, RT-PCR method has been used by many researchers to test SARS-COV-2 virus and has been widely used in clinical trials [ [75] , [76] , [77] ]. For example, Li et al developed a novel qRT-PCR method to detect SARS-COV-2 virus with a detection limit of 365.0 copies/mL.…”