Gargle lavage as a viable alternative to swab for detection of SARS-CoV-2

Abstract

Background & objectives: Nasopharyngeal and oropharyngeal swab (NPS and OPS) collection is widely accepted as the preferred method for obtaining respiratory samples. However, it has certain disadvantages which may be overcome by gargling. The primary objective of this study was to assess agreement between gargle lavage and swab as an appropriate respiratory sample for the detection of SARS-CoV-2. The secondary objective was to assess the patient acceptability of the two sampling methods. Methods: It was a cross-sectional study done at a tertiary care hospital in New Delhi, India, on 50 confirmed COVID-19 patients. Paired swab (NPS and OPS) and gargle samples were taken within 72 h of their diagnosis. Samples were processed by reverse transcription-polymerase chain reaction (RT-PCR) for detection of SARS-CoV-2. Post-sample collection, a 10-point scale was administered to assess the level of discomfort with either of the collection methods. Results: All gargle samples were positive and comparable to their corresponding swab samples irrespective of the symptoms and duration of illness. The cycle threshold (C t ) values for gargle samples were slightly higher but comparable to those of swabs. Bland-Altman plot showed good agreement between the two methods. Majority (72%) of the patients reported moderate-to-severe discomfort with swab collection in comparison to 24 per cent reporting only mild discomfort with gargle collection. Interpretation & conclusions: Our preliminary results show that the gargle lavage may be a viable alternative to swabs for sample collection for the detection of SARS-CoV-2. Adoption of gargle lavage for sample collection will have a significant impact as it will enable easy self-collection, relieve healthcare workers and also lead to substantial cost savings by reducing the need for swabs and personal protective equipment.

Field evaluation of COVID‐19 antigen tests versus RNA based detection: Potential lower sensitivity compensated by immediate results, technical simplicity, and low cost

“…Another point is the reports of a higher viral load in the samples obtained by gargle compared to those by swab pharyngeal. 12,13 Therefore, by combining the two potential sources of RNA we may maximize sensitivity and decrease health worker risk. Our study involved three health units with a lowtech laboratory, with no capacity to carry out RNA-based tests.…”

Performance of Saliva, Oropharyngeal Swabs, and Nasal Swabs for SARS-CoV-2 Molecular Detection: a Systematic Review and Meta-analysis

“…For each specimen type, in addition to data on test performance, we extracted data for factors likely to affect test performance, as detailed below. Data on throat or gargle washes were not included in this meta-analysis ( 12 , 13 ). We obtained the limit of detection (LOD) from studies by direct report within the study when available, and otherwise by manufacturer claims (package insert if available; Table S1 in the supplemental material lists how LOD was ascertained by study).…”

Self-collected gargle specimen as a patient-friendly sample collection method for COVID-19 diagnosis in a population context

“…Posterior oropharyngeal saliva and gargle lavage have been reported to show promising performance compared to nasopharyngeal and oropharyngeal swabs for the detection of COVID-19 [10,11,[17][18][19] and other respiratory viruses [20]. Goldfarb et al (2020) found that self-collected gargle specimens are more sensitive and more acceptable than saliva samples in outpatient cohorts.…”