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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
TABLE 1 - Causes of False Positive SARS-CoV-2 RT-PCR Results
Contamination during
Sampling (eg, an infected worker or surfaces; aerosolization of virus during collection)
Extraction (eg, aerosolization in containment hood)
PCR amplification
Production of Lab Reagents (eg, manufacturers of the positive control may have contaminated other reagents produced in the same facility; contamination of other consumables)
Contamination of the equipment by high viral titer specimens (eg, sample carryover)
Cross-reaction with other viruses (eg, other coronaviruses)
Sample mix-ups
Software problems
Data entry or transmission errors
Miscommunicating results
Variations in parameters around the LOD and definition of an indeterminate result
Assuming that an indeterminate result is a positive
Non-specific reactions
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
