Gargled water samples may be viable alternative to swabs for detection of Covid: Study

Gargled water samples may be viable alternative to swabs for detection of COVID-19, enabling easy self-collection and removing the need for trained healthcare workers for sample collection, according to a study published in the ICMR’s Indian Journal of Medical Research. Adoption of gargle lavage for sample collection will have a significant impact as it also leads to substantial cost savings by reducing the need for swabs and personal protective equipment, the study highlighted.

The authors of the study “Gargle lavage as a viable alternative to swab for detection of SARS-CoV-2” include Dr Naveet Wig, Dr Manish Soneja, Dr Neeraj Nischal and Dr Ankit Mittal from the department of Medicine at AIIMS, Dr Anjan Trikha and Dr Kapil Dev Soni from the department of Anaesthesia and Critical Care Medicine at AIIMS among others.

“Swab collection has several drawbacks also as it requires training, exposes the healthcare workers to the virus containing aerosols, has poor patient acceptability and is resource intensive. “An alternative sample collection method that could overcome most of these limitations without compromising the yield of the test is the need of the hour,” the study underlined.

One such method is the collection of gargle lavage, it mentioned. Although the use of gargle specimens is not new, at present, there is little published information on the suitability of gargle specimens to diagnose SARSCoV-2 infection, the study stated. This study was, therefore, conducted to assess the performance of gargle lavage in comparison to nasopharyngeal and oropharyngeal swabs for the detection of novel coronavirus.

This was a cross-sectional study conducted at the AIIMS, New Delhi over a period of one month (May-June) on 50 confirmed COVID-19 patients. Paired swab and gargle samples were taken within 72 hours 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, the study said. “All gargle samples were positive and comparable to their corresponding swab samples irrespective of the symptoms and duration of illness. The cycle threshold (Ct ) values for gargle samples were slightly higher but comparable to those of swabs. Bland-Altman plot showed good agreement between the two methods,” the study said.

Majority (72 per cent) of the patients reported moderate-to-severe discomfort with swab collection in comparison to 24 per cent reporting only mild discomfort with gargle collection. “In conclusion, the study highlights the usefulness of gargle lavage as an appropriate respiratory sample collection method. “It is a viable alternative to conventional swab collection with several distinct advantages and will have significant clinical and public health impacts in terms of better acceptability, easy self-collection, sparing of healthcare workers and cost-effectiveness,” the study said.

The major limitation of this study was its cross-sectional design and it was performed only on a limited number of positive cases. In addition, it would be necessary to evaluate the performance using different viral RNA isolation platforms, the study said.