Nasopharyngeal swabs have been used for decades to diagnose respiratory infections, including COVID-19. A trained healthcare professional takes the sample by inserting a long swab through the nose to an area at the back of the nasal cavity called the posterior nasopharynx. Despite their widespread use however, there is no universally agreed upon optimal technique to collect these swabs. Certain guidance notes instruct care providers to rotate in the swab in place for up to 10 seconds after contacting the back of the nasal cavity, while others say this is not necessary. It is important to know, however, because rotation makes the procedure take longer, and may increase discomfort for the person undergoing the test.
To address this knowledge gap, Faculty of Health Sciences (FHS) PhD students Natalie Kinloch and Aniqa Shahid, who are also research assistants at the BC Centre for Excellence in HIV/AIDS, assessed whether rotation of the swab improved the quality of a collected specimen.
Working with FHS professor Zabrina Brumme and Dr. Victor Leung, the Medical Director of Infection Prevention and Control at Providence Health Care, the team recruited 69 volunteers for the study and assigned them to receive nasopharyngeal swabs either with or without rotation. Volunteers were also asked to rate their discomfort during the procedure.
Kinloch and Shahid then used a technique called droplet digital polymerase chain reaction (ddPCR) to measure the quantities of human DNA and RNA recovered on the swabs, as surrogate markers of specimen collection quality.
The results surprised the researchers: they found that responses from the participants suggested that swab rotation made their experience more uncomfortable. Additionally, “we found that, despite widespread recommendation, rotation of the swab did not recover more biological material,” said Kinloch. “The study’s first major conclusion was therefore that swab rotation was unnecessary.”
“When asked to rate their discomfort on a scale from zero to 10, participants’ responses ranged from 1 to 10,” said Shahid. “This means that care providers should be sensitive to such differences in experience between individuals when performing the procedure.”