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Evidence for Limited Early Spread of COVID-19 Within the United States, January–February 2020
"retrospective SARS-CoV-2 testing of approximately 11,000 respiratory specimens from several U.S. locations beginning January 1 identified no positive results before February 20...
...The findings in this report are subject to at least three limitations. First, the data presented here are retrospective."
In this thread I will show that the lack of false positives makes these findings highly implausible, and I will show that other studies have had contradictory results.
Jorden MA, Rudman SL, et al. Evidence for Limited Early Spread of COVID-19 Within the United States, January–February 2020. MMWR Morb Mortal Wkly Rep 2020;69:680–684. DOI: http://dx.doi.org/10.15585/mmwr.mm6922e1
"The most widely utilized Nucleic Acid Amplification Test (NAAT) to detect SARS-CoV-2 RNA is the reverse transcriptase-polymerase chain reaction (RT-PCR) test, manufactured by many companies targeting one or more genomic regions of the virus...
...The FDA has published recommendations concerning the data and information that test manufacturers should supply in their application for Emergency Use Authorization (EUA)...
...Acceptable clinical performance is defined as a minimum 95% positive and negative percent agreement (PPA and NPA).
For a screening indication, the PPA recommendation remains at more than or equal to 95% and the NPA is raised to more than or equal to 98% to reduce false positive test results.
In actual use, the clinical sensitivity and specificity of many of these tests is lower in part because of issues surrounding sample collection, handling, and analysis."
Braunstein, Glenn D. MD; Schwartz, Lori MD, FACOEM; Hymel, Pamela MD, MPH, FACOEM; Fielding, Jonathan MD, MPH, MBA. False Positive Results With SARS-CoV-2 RT-PCR Tests and How to Evaluate a RT-PCR-Positive Test for the Possibility of a False Positive Result. Journal of Occupational and Environmental Medicine 63(3):p e159-e162, March 2021. | DOI: 10.1097/JOM.0000000000002138
