key: cord-0703190-kbbd8li2
authors: Jaafar, Rita; Aherfi, Sarah; Wurtz, Nathalie; Grimaldier, Clio; Hoang, Van Thuan; Colson, Philippe; Raoult, Didier; La Scola, Bernard
title: Correlation between 3790 qPCR positives samples and positive cell cultures including 1941 SARS-CoV-2 isolates
date: 2020-09-28
journal: Clin Infect Dis
DOI: 10.1093/cid/ciaa1491
sha: 7ff617aa4d3bcf75bac5d44069d9984fa9ec91ba
doc_id: 703190
cord_uid: kbbd8li2

nan

M a n u s c r i p t 2 Dear Editor -Since the beginning of the outbreak of the emerging epidemic (Covid-19) due to SARS-CoV-2, declared as a pandemic on March 12 th 2020 by the WHO [1], a major issue has been to correlate viral RNA load obtained after RT-PCR and expressed in cycle threshold (Ct) with contagiousness and therefore duration of eviction from contacts and discharge from specialized infectious disease wards. Several works published recently and based on more than 100 studies attempt to propose such cut off for Ct value and duration of eviction with a consensus at approximately Ct > 30 and at least 10 days, respectively [2] [3] [4] [5] . However, in an article published in this journal, a group reported that patients could be not be contagious above 25 Ct as the virus was not detected in culture above this Ct [6] . This limit was then our laboratory and initial results of cultures [8] is validated by the present work and is in correlation with what was proposed i.e. in Korea [9] or Taiwan [10] . We could observe that subcultures, especially the first one, allow increasing percentage of viral isolation on high Ct samples, confirming that these high Ct are mostly correlated with low viral loads. From our cohort, we now need to try to understand and define the duration and frequency of live virus shedding in patients on a case-by-case basis, in the rare cases where the PCR is positive beyond 10 days, often at a Ct above 30. In any cases, these rare cases should not impact public health decisions. A c c e p t e d M a n u s c r i p t A c c e p t e d M a n u s c r i p t Figure 1 

Viral cultures for COVID-19

Duration of SARS-CoV-2 Infectivity: When is it Safe to Discontinue Isolation?

Duration of infectiousness and correlation with RT-PCR cycle threshold values in cases of COVID-19

SARS

CoV-1 and MERS-CoV viral load dynamics, duration of viral shedding and infectiousness: a living systematic review and meta-analysis. Infectious Diseases (except HIV/AIDS)

Predicting Infectious Severe Acute Respiratory Syndrome Coronavirus 2 From Diagnostic Samples

Viral RNA load as determined by cell culture as a management tool for discharge of SARS-CoV-2 patients from infectious disease wards

Interpreting the COVID-19 Test Results: a Guide for

Optimization of the CDC Protocol of Molecular Diagnosis of COVID-19 for Timely Diagnosis

Ethical approval :

A c c e p t e d M a n u s c r i p t