• Duane J Funk, Jared Bullard, Sylvan Lother, Gloria Vazquez Grande, Lauren Garnett, Kaylie Doan, Kerry Dust, Anand Kumar, Guillaume Poliquin, and Jim Strong.
• Departments of Anesthesiology and Medicine, Section of Critical Care, Max Rady College of Medicine, University of Manitoba, 2nd Floor Harry Medovy House, 671 William Avenue, Winnipeg, MB, R3E 0Z2, Canada. Duane.Funk@Umanitoba.ca.
• Crit Care. 2022 Jan 4; 26 (1): 10.

BackgroundResearch on the duration of infectivity of ICU patients with COVID-19 has been sparse. Tests based on Reverse Transcriptase polymerase chain reaction (RT-PCR) detect both live virus and non-infectious viral RNA. We aimed to determine the duration of infectiousness based on viral culture of nasopharyngeal samples of patients with COVID-19.MethodsProspective observational study in adult intensive care units with a diagnosis of COVID-19 Pneumonia. Patients had repeated nasopharyngeal sampling performed after day 10 of ICU admission. Culture positive rate (based on viral culture on Vero cells in a level 4 lab) and Cycle threshold from RT-PCR were measured.ResultsNine patients of the 108 samples (8.3%, 95% CI 3.9-15.2%) grew live virus at a median of 13 days (interquartile range 11-19) after their initial positive test. 74.1% of patients were RT-PCR positive but culture negative, and the remaining (17.6%) were RT-PCR and culture negative. Cycle threshold showed excellent ability to predict the presence of live virus, with a Ct < 25 with an AUC of 0.90 (95% CI 0.83-0.97, p < 0.001). The specificity of a Ct > 25 to predict negative viral culture was 100% (95% CI 70-100%).Conclusion8.3% of our ICU patients with COVID-19 grew live virus at a median of 13 days post-initial positive RT-PCR test. Severity of illness, use of mechanical ventilation, and time between tests did not predict the presence of live virus. Cycle threshold of > 25 had the best ability to determine the lack of live virus in these patents.© 2022. The Author(s).

16 keywords...

hide…