[MCOH-EH] Fw: Warning-False Positives in Low Incidence Populations

[Tom Kibby]

 Am I the first to speak up on this?

This letter comes in the context of employers ramping up mandatory vaccination programs with regular testing as the alternative for vaccination resisters or those with medical exemptions. The goal is to keep contagious workers out of the workplace, a worthy goal the the vaccinated workers and their employers usually welcome. So the burden of testing falls only on the un-vaccinated and those footing the bill. False positive tests are a given in any testing program. When the CDC evaluated one of the more popular tests, Abbott's BinaxNOW (MMWR 70 (3); 100-105) it reported a low 35% sensitivity for this test in asymptomatic individuals, and a 99.8% specificity in the asymptomatic. 
First, if this testing program is "risky and harmful" it is from the terrible sensitivity of these tests, which allow asymptomatic individuals into the workplace where co-workers will mingle with a false sense of security.  Which supports the recommendation of universal indoor masking. Second, this letter does not consider the likely use of serial or follow-up testing. When a worker screens positive, most programs will exclude them from the workplace and allow them to seek additional testing. Return to work would be dependent on a negative PCR test and likely a negative symptom screen. So then then actual false positive rate after two sequential tests would be under one per 100,000.
Is the point to speak up against unfair treatment of unvaccinated workers subjected to testing? I hope not.
Thomas Kibby, MD MPHWashington U. Preventive Medicine



From: docfjs via MCOH-EH <mcoh-eh at mylist.net>
Date: August 31, 2021 at 6:53:09 PM CDT
To: mcoh-eh at mylist.net
Cc: docfjs <docfjs at yahoo.com>
Subject: [MCOH-EH] Warning-False Positives in Low Incidence Populations
Reply-To: MCOH-EH <mcoh-eh at mylist.net>



Testing asymptomatic individuals, who by the very fact that they are not symptomatic, constitute a low incidence population is risky and in my opinion harmful.   The lower the incidence of the disease in the population, the higher the number of false positives.  This is a statistical law, and is why smart physicians always try to test individuals how have a high likelihood of having the illness they are testing for.  For example, in the case of COVID fever, cough, loss of sense of smell or documented exposureThe following article shows that in a population where incidence is 1%, the percentage of false positives is 40%,False Positives in PCR Tests for COVID-19 - ICD10monitor


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False Positives in PCR Tests for COVID-19 - ICD10monitor

Andrew N. Cohen, PhD

The prevalence of misinformation coming from the most trusted form of coronavirus test may be more significant t...
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