Duration of Infectious Virus Shedding in Patients with Severe Coronavirus Disease 2019 Who Required Mechanical Ventilation

Background: Around 5% of patients with coronavirus disease ( COVID-19) caused by severe acute respiratory syndrome coronavirus 2 develop severe COVID-19. Severe COVID-19 requires respiratory management with mechanical ventilation and an extended period of treatment. Prolonged infectious virus shedding is a concern in severe COVID-19 cases, but few reports have examined the duration of infectious virus shedding. We investigated the duration of infectious virus shedding in patients transferred to Hiroshima University Hospital with severe COVID-19 requiring mechanical ventilation. Methods: Nasopharyngeal swab specimens were collected and analyzed using both viral culture and reverse transcriptase-quantitative polymerase chain reaction (RT-qPCR) tests between December 2020 and February 2021. Findings: Of the 23 patients tested, the percentage of those with positive test results at first specimen collection (the median number of days to first specimen collection after symptom onset was ten) on RT-qPCR and viral culture was 95 ·7% (n = 22) and 30·4% (n = 7), respectively. All six patients with positive viral culture test results who were followed-up tested negative by day 24 after symptom onset but remained positive on RT-qPCR. Specimen viral loads based on PCR testing did not decrease over time, but viral loads determined via culture tests loads decreased over time. The longest negative conversion time was observed in a dialysis patient on immunosuppressive drugs. Interpretation: This study indicated that patients with severe COVID-19 remain culture positive ≥ ten days after symptom onset. The work also suggests that immunosuppressed patients with severe COVID-19 could consider isolation for ≥ 20 days. Funding: None Declaration of Interests: We declare no competing interests. Ethics Approval Statement: This research was approved by the Ethical Committee for Epidemiology of Hiroshima University (approval number: E-2157).