COVID-19 study led by PhD student identifies improper sample collection as a source of false-negative test results

Faculty of Health Sciences (FHS) PhD student and Vanier scholar Natalie Kinloch recently led a study that was published in the Journal of Infectious Diseases, showing that improper collection of nasopharyngeal swabs is a major cause of false-negative COVID-19 diagnostic tests.

She has been with the Faculty of Health Sciences since 2010, completing a BSc (Honours) in Health Sciences, and is currently completing her PhD under the mentorship of FHS professor Zabrina Brumme. Kinloch has always been interested in viruses and genetics, and has been working in Brumme’s lab investigating HIV genetic diversity and evolution with the goal of informing the design of both an HIV vaccine and cure. Kinloch is now applying her skills towards improving our understanding of SARS-CoV-2 and refining our clinical response to the COVID-19 pandemic.

Kinloch’s study looked at human DNA levels recovered on nasopharyngeal swabs submitted to the Virology Laboratory at St. Paul’s Hospital, one of five provincially designated COVID-19 testing labs, hypothesizing that human DNA could serve as a stable molecular marker of specimen collection quality.

Her study compared human DNA levels between 40 suspected false-negative nasopharyngeal swab test results from presumed or confirmed COVID-19 cases and a representative pool of 87 specimens submitted for COVID-19 testing. She found that there were significantly lower human DNA levels on the swabs that yielded negative diagnostic test results (i.e. suspected false-negative test results) compared to the representative pool of specimens.

Her observations strongly suggest that suboptimal biological sampling is a contributing cause of false-negative COVID-19 test results. This underscores the importance of proper training and technique in the collection of high quality nasopharyngeal specimens.

A follow-up study will be conducted later this summer, with healthy volunteers undergoing nasopharyngeal swab sampling using one of two techniques commonly used by a trained healthcare professional. The goal is to refine collection techniques and practices in BC by identifying the technique that recovers the largest amount of biological material while minimizing discomfort for the person undergoing the procedure.

This study was funded by a Genome BC COVID-19 rapid response grant.