When the SARS-CoV-2 virus began spreading, and COVID-19 was declared a pandemic, much of the physician services healthcare community was focused on diagnostic test availability so that we could identify those who had been infected with the virus and use that information to slow the spread of the disease. Now, however, attention has shifted from availability to accuracy. A new Perspective article in the New England Journal of Medicine discusses the challenges and implications related to inaccurate test results associated with COVID-19 diagnostics.
The authors point to the relative importance of minimizing false negative tests because, while false positive test results lead to unnecessary quarantine measures and contact tracing, false negative test results can be more damaging because they misinform infected people who can then unknowingly spread the virus. Based on this reality, the U.S. Food and Drug Administration (FDA) has granted commercial test manufacturers the Emergency Use Authorizations (EUAs) to facilitate COVID-19 test validation for reverse transcriptase polymerase chain reaction (RT-PCR) tests, which are the tests that are deployed to identify current infection (versus previous infection, which is analyzed with an antibody test).
Validation measures aim to determine test sensitivity, or the likelihood that an infected sample will indeed produce a positive test result, as well as test specificity – i.e. the likelihood that a sample that is not infected will produce a negative test result. According to the authors, test sensitivity, which they argue is the more important measure, may only reach about 70%. In other words, 30% of people who take a test and who are infected will get a negative test result. The authors claim that this level of false negative tests needs to be lowered and point to strategies to help improve our ability to accurately diagnose people who have been infected with the virus causing COVID-19. By improving our ability to rapidly identify those who are infected, the hope is that we can more effectively stop the spread.
Woloshin S, Patel N, Kesselheim AS. False Negative Tests for SARS-CoV-2 Infection – Challenges and Implications. N Engl J Med. June 2020. doi:10.1056/NEJMp2015897