Daily Covid tests positives and percent positive

Latest data is from end of day on September 23rd, 2021

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Graph of Covid-19 PCR Tests by published date and positive results by specimen date (defaults log scale and 7 day rolling average)

Data source

There has been no firm official figure for the false positive rate with the Covid PCR testing. It is questionable whether any reported infections of less than 1% represent anything other than false positives. Many of those tested as postive may also just be carrying fragments of virus from exposure or past infection and not be infectious to others.


False positives a non-technical explanation.

The authors of a recent preprint (a paper which hasn't yet been peer-reviewed, or independently verified by other researchers) undertook a review of the evidence on false positive rates for the RT-PCR test used to detect SARS-CoV-2.

They combined the results of multiple studies (some looked at PCR testing for SARS-CoV-2 specifically, and some looked at PCR testing for other RNA viruses). They found false positive rates of 0-16.7%, with 50% of the studies at 0.8-4.0%.

The false positive rates in the systematic review were mainly based on quality assurance testing in laboratories. It's likely that in real world situations, accuracy is poorer than in the laboratory studies.


Naturally there are false negatives too but there is no consensus on those.


False positives Select a value to check the impact. Default is 0.8%



Linear scale     Log scale    Raw data    Rolling average (default:7)




Graph of Covid-19 percent positive results with no false positive correction (defaults linear scale and 7 day rolling average)


There has been no firm official figure for the false positive rate with the Covid PCR testing. It is questionable whether any reported infections of less than 1% represent anything other than false positives. Many of those tested as postive may also just be carrying fragments of virus from exposure or past infection and not be infectious to others.


Linear scale     Log scale    Raw data    Rolling average (default:7)




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