key: cord-253472-3s142p6u authors: Saurabh, Suman; Bhardwaj, Pankaj title: Author’s reply to correspondence regarding the article ‘Prolonged persistence of SARS-CoV-2 in the upper respiratory tract of asymptomatic infected individuals’ date: 2020-09-18 journal: QJM DOI: 10.1093/qjmed/hcaa269 sha: doc_id: 253472 cord_uid: 3s142p6u nan We appreciate the interest shown by Kadnur and Ray regarding our article 1 through their correspondence. We offer a reply to the points raised by them. They have appropriately mentioned that there has been a paradigm shift in the discharge policy in India from test-based to symptom plus duration based now. 2 This has also been mentioned by us in the article. 1 They have also referenced CDC, USA guidelines to state that infection prevention precautions be discontinued after 10 days for most COVID-19 patients. 3 However, it is important to note that in India, the Ministry of Health and Family Welfare (MoHFW) guidelines are being followed. 2 It recommends home isolation for 17 days after symptom onset or remaining in home isolation for 7 days after being discharged from a 10 days-hospital stay. 2 We have taken this home-isolation duration of 17 days as the base and have recommended its extension to 21 days (3 weeks), as applicable to the Indian situation. 1 This is since 95% SARS-CoV-2 infected individuals (including both symptomatics and asymptomatics) were found to have virus persistence of up to 20.92 days. 1 Further, they go on to state that 'as per test-based strategy for asymptomatic patients, two respiratory specimens (≥ 24 hours apart) are required to be negative, irrespective of initial date of COVID-19 detection'. However, as stated earlier, testbased discharge policy has been completely discontinued in India starting 8 May 2020, in favour of a symptom plus duration-based approach. 2 This is saving considerable testing resources. Test-based discharge is not practicable with an overwhelming number of SARS-CoV-2 infected individuals and a large proportion of them undergoing home isolation. That said, some tertiary care centres might still be following a test-based approach, but this is not as per the national policy. 2 We only referenced Bullard et al in stating that higher viral load indicated by cyclic threshold values < 24 correlates with cell culture infectivity which is a laboratory finding. 8 Since we didn't have cyclic threshold values which could be compared between asymptomatics and symptomatics, we had opined that there could be infection spreaders even among asymptomatics when individuals with varying viral loads were considered in a large population. 1 Variation in findings of SARS-CoV-2 persistence might be found due to viral and host characteristics and difference in study procedures. Replication competence in cell culture is dependent on laboratory expertise, cell lines and protocols used 9,10 due to which they could be limited in their ability to predict the infectious process in realworld situation. Therefore, we feel that all available evidence should be appraised for development of COVID-19 guidelines and a selective approach is best avoided. Implementing reduced duration of infection prevention precautions without cautiously assessing evidence could weaken the objective of interrupting SARS-CoV-2 transmission. We maintain that there is nothing contradictory in the recommendations of our study which are based on our own findings. Emerging evidence can of course lead to better understanding of disease process and transmission dynamics which could prompt amendment in guidelines. Prolonged persistence of SARS-CoV-2 in the upper respiratory tract of asymptomatic infected individuals Ministry of Health and Family Welfare, Government of India COVID-19) Virological assessment of hospitalized patients with COVID-2019 Guidelines for home isolation among asymptomatic and mildly symptomatic COVID-19 patients Associations of clinical characteristics and treatment regimens with the duration of viral RNA shedding in patients with COVID-19 Shedding of infectious virus in hospitalized patients with coronavirus disease-2019 (COVID-19): duration and key determinants Predicting infectious SARS-CoV-2 from diagnostic samples Duration of infectiousness and correlation with RT-PCR cycle threshold values in cases of COVID-19 Viral RNA load as determined by cell culture as a management tool for discharge of SARS-CoV-2 patients from infectious disease wards AUTHOR STATEMENTS Funding-The authors declare that no funding was received from any source for the study and preparation of this author's reply. Ethical approval -Not applicable. Authors' contributions -SS wrote the first draft of the reply which was edited as per inputs provided by PB. Both authors approved the final version.