Public Accountability Unit
T 020 8327 6920
133-155 Waterloo Road
London SE1 8UG
Our ref: 22/12/hf/2212
14 January 2021
Dear Dr Jonathan Dench Re: COVID-19 PCR Test protocol, Sensitivity, Specificity and therefore
Operational False Positive Rate, and how the official figures are corrected for
Thank you for your request received on 22 December 2020 addressed to Public
Health England (PHE). In accordance with Section 1(1)(a) of the Freedom of
Information Act 2000 (the Act), I can confirm that PHE partly holds the information
you have specified.
I have some strong scientific concern about COVID-19 testing and the
handling of data by the UK Government.
Firstly no-specificity or sensitivity is provided which is completely
unacceptable. It appears data is not being corrected for the Operational false
positive rate of such tests. Current estimates of specificity from the literature
are 95-99% ,this does not sound alarming at first, but once you account for
test frequency and prevalence this is quite alarming, as it would provide an
operational false positive rate of 90%. This can be confirmed from "with COVID
death' data ie died within 28 days of positive PCR. If you compare current
excess death with the average of the past 5 years with the governments
estimates of COVID death, you get an Operational false positive rate of 70% for
a sample with the highest pre-test probability of having COVID and therefore
the lowest OFPR. This means the government statistics are meaningless
without correction. This also means no mass indescriminate testing should
take place as this would further worsen this problem. You should be doing a
full investigation on this matter, as the Government draws us further into a
What I am requesting:
Full PCR test protocol
How data is being corrected for Operational false positive rate.
PHE does not hold the requested information on the full PCR test protocol, test
sensitivity and test specificity.
There are multiple tests being used and every kit will have its own interpretative
criteria and thresholds, as recommended by the manufacturer. PHE evaluation is not
mandatory for COVID-19 diagnostic tests and assays. PHE has undertaken rapid
assessment of commercially provided diagnostic tests with further evaluations
ongoing, please refer to this link for further information on PHE’s work in this area https://www.gov.uk/government/collections/covid-19-phe-assessment-of-laboratory-
The Medicines and Health Products Regulatory Agency is the national regulator for
medical tests and any test can legally be marketed and deployed in the UK once it
receives a CE mark. For further information refer to this link https://www.gov.uk/government/publications/how-tests-and-testing-kits-for-
Regarding the operational false positive rate, daily reported case numbers exclude
results that have been identified as false. Where confirmatory tests are undertaken,
results are only reported when they have been confirmed.
If you have any queries regarding the information that has been supplied to you,
please refer your query to me in writing in the first instance. If you remain dissatisfied
and would like to request an internal review, then please contact us at the address
above or by emailing firstname.lastname@example.org.
Please note that you have the right to an independent review by the Information
Commissioner’s Office if a complaint cannot be resolved through the PHE
complaints procedure. The Information Commissioner’s Office can be contacted by
calling the ICO’s helpline on 0303 123 1113, visiting the ICO’s website at www.ico.org.uk
or writing to the ICO at Wycliffe House, Water Lane, Wilmslow,
Cheshire, SK9 5AF.