Suboptimal biological sampling as a probable cause of false-negative COVID-19 diagnostic test results.

False-negative SARS-CoV-2 test results can negatively impact the clinical and public health response to COVID-19. We used droplet digital PCR (ddPCR) to demonstrate that human DNA levels, a stable molecular marker of sampling quality, were significantly lower in samples from 40 confirmed or suspected COVID-19 cases that yielded negative diagnostic test results (i.e. suspected false-negative test results) compared to a representative pool of 87 specimens submitted for COVID-19 testing. Our results support suboptimal biological sampling as a contributor to false-negative COVID-19 test results and underscore the importance of proper training and technique in the collection of nasopharyngeal specimens.