Comparative Evaluation of Tears and Nasopharyngeal Swab for SARS-CoV-2 in COVID-19 Dedicated Intensive Care Unit Patients

Abstract

Purpose: To compare the cycle threshold (Ct) values of tears and nasopharyngeal (NP) swab in severe COVID-19 ICU patients with positive NP swabs.Procedure: A cross-sectional study for the detection of SARS-CoV-2 by real-time RT-PCR on simultaneously collected NP swabs and tears was performed. Detailed demographic profile, including comorbidities, ocular, and systemic features were analyzed.Results: In the 78 cases, the mean tear positivity was 26.92% (21/78), 2 tear samples being positive despite a negative NP swab. The mean Ct value of tears and NP were 28.17 ± 4.76 and 23.71 ± 6.19, respectively (p= .003). None of the cases had ocular findings or relationship between tear positivity and comorbidity.Conclusions: The viral load of tears is less than the NP secretions with the possibility of prolonged shedding in tears. Tears act as an additional source of contact transmission in ICU that can possibly be decreased by frequent hand hygiene by the patient.Abbreviations: SARS-CoV-2: Severe acute respiratory syndrome coronavirus; RT-PCR: Real-time Reverse transcriptase-polymerase chain reaction; COVID-19: Corona virus disease 2019; ICU: Intensive care unit; RdRp: RNA-dependent RNA polymerase; ORF 1b: Open reading frame 1b; AIIR: Airborne infection isolation room; HCW: Health care workers; VTM: viral transport media; NP: Nasopharyngeal swab; PPE: Personal protective equipment.

Keywords: COVID-19; RT-PCR; SARS-CoV-2; tear positivity; transmission.