Diagnosing COVID-19 infection: the danger of over-reliance on positive test
results
The evidence shows that false positive PCR results are common enough to
impact clinical and policy decisions.
Andrew N. Cohen, Ph.D.1
*, Bruce Kessel, M.D.2
, Michael G. Milgroom, Ph.D.3
1
Center for Research on Aquatic Bioinvasions, Richmond CA, USA. acohen@bioinvasions.com
2
John A. Burns School of Medicine, University of Hawai’i, Honolulu HI, USA.
bkessel@queens.org
3
School of Integrative Plant Science, Plant Pathology and Plant-Microbe Biology Section,
Cornell University, Ithaca NY, USA. mgm5@cornell.edu
* Corresponding author
Abstract: Unlike previous epidemics, in addressing COVID-19 nearly all international
health organizations and national health ministries have treated a single positive result
from a PCR-based test as confirmation of infection, even in asymptomatic persons
without any history of exposure. This is based on a widespread belief that positive
results in these tests are highly reliable. However, data on PCR-based tests for similar
viruses show that PCR-based testing produces enough false positive results to make
positive results highly unreliable over a broad range of real-world scenarios. This has
clinical and case management implications, and affects an array of epidemiological
statistics, including the asymptomatic ratio, prevalence, and hospitalization and death
rates. Steps should be taken to raise awareness of false positives, reduce their
frequency, and mitigate their effects. In the interim, positive results in asymptomatic
individuals that haven’t been confirmed by a second test should be considered suspect.