Covid samples from cheeks

Naina Mishra
Tribune News Service
Chandigarh, May 26

The PGI has found that Covid-19 can also be traced by self-collection of “buccal swab” in suspected patients. It was found the sensitivity of RT-PCR from buccal swabs was 58.9% and that of saliva 62.90%.

What results of the study say

RT-PCR results from NPS samples were used as the gold standard to gauge the diagnostic capability of RT-PCR from buccal and saliva samples. The study included both asymptomatic (n=59) and symptomatic (n=14) patients whose NPS samples were found positive for Covid by RT-PCR. Of 73 buccal swabs, 43 (58.90%) were positive by RT-PCR and of 62 saliva samples, 39 (62.90%) were positive for SARS-CoV-2 by RT-PCR. In the 30 patients whose buccal swabs were negative, 10 had positive saliva samples. Conversely, buccal swabs tested positive for six of the 23 patients in whom saliva was negative by RT-PCR. Sampling by NPS was found to be most sensitive, followed by saliva, with buccal swabs being the least sensitive.

In this study conducted by doctors of the PGI, buccal swabs were self-collected by patients using sterile nylon-tipped swabs. Patients were asked to place the swab in between the forefinger and thumb and insert the flocked swab into one side of the mouth between the cheek and the upper gum. The patients exercised the same precautions as those used for saliva collection.

The study assessed self-collected buccal swab samples as an alternative method for SARS-CoV-2 detection in patients.

The current gold standard for detection of Covid-19 involves subjecting nasopharyngeal or oropharyngeal swabs (NPS) to RT-PCR. However, both sample types need to be collected by trained professionals. The intent of using this technique was that using self-collected buccal swabs as an alternative could simplify and accelerate diagnosis of Covid-19.

“Although NPS sampling remains the gold standard, it must be recognised that there are specific patient groups that are not amenable with regard to this procedure. These patients require diagnostic testing as well and can benefit from alternative testing modalities such as saliva and buccal swab sampling,” the study concluded.