key: cord-0971076-jztjnh0v
authors: Aranha, Clara; Patel, Vainav; Bhor, Vikrant; Gogoi, Dimpu
title: Cycle threshold values in RT‐PCR to determine dynamics of SARS‐CoV‐2 viral load: An approach to reduce the isolation period for COVID‐19 patients
date: 2021-07-23
journal: J Med Virol
DOI: 10.1002/jmv.27206
sha: 64c5cebb62c951716bf90e4d8b7811cb326d9b50
doc_id: 971076
cord_uid: jztjnh0v

Severe acute respiratory syndrome coronavirus (SARS‐CoV‐2) has affected all inhabited continents, and India is currently experiencing a devastating second wave of coronavirus disease‐2019 (COVID‐19). Here, we examined the duration of clearance of SARS‐CoV‐2 in respiratory samples from 207 infected cases by real‐time reverse‐transcription polymerase chain reaction (RT‐PCR). A substantial proportion of COVID‐19 positive cases with cycle threshold (Ct) values more than or equal to 31 (45.7%) were subsequently tested negative for SARS‐CoV‐2 RNA within 7 days of initial detection of the viral load. A total of 60% of all the patients with COVID‐19, irrespective of their Ct values, cleared SARS‐CoV‐2 RNA within 14 days of the initial detection. Longitudinal assessment of RT‐PCR test results in individuals requiring 15–30 days to clear SARS‐CoV‐2 RNA showed a significant reduction of the viral load in samples with high or intermediate viral loads (Ct values ≤ 25 and between 26 and 30, respectively) but the follow‐up group with low viral RNA (Ct values ≥ 31) exhibited a stable viral load. Together, these results suggest that COVID‐19 positive cases with Ct values more than or equal to 31 require reduced duration to clear SARS‐CoV‐2, and thus, a shorter isolation period for this group might be considered to facilitate adequate space in the COVID Care Centres and reduce the burden on healthcare infrastructure.

reported the first confirmed case of COVID-19 on January 30, 2020, and the cases rose exponentially in the next 8 months, the highest peak was recorded in the middle of September and then the caseload started declining for the next few months. However, India is witnessing the second wave of COVID-19 pandemic since the first half of April 2021. The raging wave has greatly impacted the healthcare system with a deficiency in beds, oxygen, and medical supplies. The respiratory illness is transmitted in the community through respiratory droplets and contacts of infected people. 1,2 SARS-CoV-2 infection could be asymptomatic or symptomatic and the viral load is not associated with disease severity. 3 The most common symptoms reported in patients are fever, fatigue, sore throat, dry cough, and breathlessness whereas headache, dizziness, abdominal pain, diarrhea, nausea, and vomiting are the less common symptoms. 4 Real-time reverse-transcription polymerase chain reaction (RT-PCR) test has been routinely used as the diagnostic test to detect SARS-CoV-2 nucleic acids in respiratory specimen swabs from Statistical analyses were performed using GraphPad Prism version 5.0, the Mann-Whitney test was used as the test of significance, and Spearman's rank correlation was used for correlation analysis. This approach would support dealing with the COVID-19 pandemic and its successive waves that have overburdened the healthcare system and COVID Care Centres. 

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To interpret the SARS-CoV-2 test, consider the cycle threshold value

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An approach to lifting self-isolation for health care workers with prolonged shedding of SARS-CoV-2 RNA

Virological assessment of hospitalized patients with COVID-2019

Cycle threshold values in RT-PCR to determine dynamics of SARS-CoV-2 viral load: An approach to reduce the isolation period for COVID-19 patients

We thank ICMR-NIRRH COVID-19 team members for their support in testing and reporting SARS-CoV-2 infection. We also thank the Director, ICMR-NIRRH for her continued support.

The authors declare that there are no conflicts of interest. 

http://orcid.org/0000-0001-5513-3298