One of the most commonly used diagnostic tools, particularly during this pandemic, is the reverse transcriptase polymerase chain reaction test (RT-PCR), which uses a person’s respiratory sample to detect viral particles and determine if the person may have been exposed to a virus.
RT-PCR used across the U.S. and the globe to find out if a person has been infected with SARS-CoV-2
Laboratory professionals across the U.S. and the globe have used RT-PCR to find out if a person has been infected with SARS-CoV-2, the virus that causes COVID-19. These tests have played a critical role in our nation’s response to the pandemic. But, while they are important, researchers at Johns Hopkins have found that the chance of a false negative result — when a virus is not detected in a person who actually is, or recently has been, infected — is greater than 1 in 5 and, at times, far higher. The researchers caution that the predictive value of these tests may not always yield accurate results, and timing of the test seems to matter greatly in the accuracy.
Researchers caution that the predictive value of these tests may not always yield accurate results
In the report on the findings published May 13 in the journal Annals of Internal Medicine, the researchers found that the probability of a false negative result decreases from 100% on Day 1 of being infected to 67% on Day 4. The false negative rate decreased to 20% on Day 8 (three days after a person begins experiencing symptoms). They also found that on the day a person started experiencing actual symptoms of illness, the average false negative rate was 38%. In addition, the false negative rate began to increase again from 21% on Day 9 to 66% on Day 21.
False negative rate began to increase again from 21% on Day 9 to 66% on Day 21
The study, which analyzed seven previously published studies on RT-PCR performance, adds to evidence that caution should be used in the interpretation of negative test results, particularly for individuals likely to have been exposed or who have symptoms consistent with COVID-19.
1. Lauren M. Kucirka, Stephen A. Lauer, Oliver Laeyendecker, Denali Boon, Justin Lessler. Variation in False-Negative Rate of Reverse Transcriptase Polymerase Chain Reaction–Based SARS-CoV-2 Tests by Time Since Exposure. Annals of Internal Medicine, 2020; DOI: 10.7326/M20-1495
Razi Berry is the founder and publisher of the journal Naturopathic Doctor News & Review, which has been in print since 2005, and the premier consumer-faced website of naturopathic medicine, NaturalPath. She is the host of The Love is Medicine Project docuseries, The Natural Cancer Prevention Summit, The Heart Revolution-Heal, Empower and Follow Your Heart, and the popular 10-week Sugar Free Summer program. From a near death experience as a young girl that healed her failing heart, to later overcoming infertility and chronic fatigue syndrome and fibromyalgia through naturopathic medicine, Razi has lived the mind/body healing paradigm. Her projects uniquely capture the tradition and philosophy of naturopathy: The healing power of nature, the vital life force in every living thing and the undeniable role that science and mind/body medicine have in creating health and overcoming dis-ease. You can follow Razi on social media: Facebook at Razi Berry, Instagram at Razi.Berry and join the Love is Medicine group to explore the convergence of love and health. Look for more, and listen to more Love is Medicine podcast episodes here.