Self-collected mouth samples a good option for Covid testing: PGI study
Self-collected buccal (cheek) samples are promising alternatives to nasal and throat swab culture for Covid testing, a study by researchers at the Post Graduate Institute of Medical Education and Research and Panjab University has noted.
The researchers stated that nasopharyngeal (nose) and oropharyngeal (throat) swab sampling remains the gold standard for reverse transcription-quantitative polymerase chain reaction (RT-qPCR) tests as these methods have established track records for detection of respiratory viruses and have been widely used in pandemic situations. However, these pose unique challenges, such as requiring the healthcare worker to be in close proximity to the infected patient, which can be risky in the backdrop of a public health emergency.
In addition, these induce discomfort and can stimulate the gag reflex (contraction of the throat that happens when something touches the roof of the mouth) in patients undergoing sampling. This can affect compliance and carries the risk of aerosol generation.
Nasal and throat sampling also require the use of personal protective equipment (PPE). Researchers noted that although nasopharyngeal sampling remains the gold standard, it must be recognised that there are specific patient groups that are not amenable to this procedure. For instance, it can be difficult to obtain nasal and throat samples from children and adults with various health conditions.
Compared with nasal and throat sampling, the sensitivity of tests from buccal swabs and saliva was 58.90% and 62.90%, respectively suggesting that the oral cavity and its fluids are of high relevance to the pathophysiology of SARS-CoV-2.
“Results from nose and throat samples were used as the gold standard to gauge the diagnostic capability from buccal and saliva samples. Both asymptomatic (59) and symptomatic (14) patients, whose nose and throat samples were positive for SARS-CoV-2 by RT-qPCR, were included in our study. Of 73 buccal swabs, 43 (58.90%) were found positive for SARS-CoV-2 and of 62 saliva samples, 39 (62.90%) were positive for SARS-CoV-2.”