Public Accountability Unit
T 020 8327 6920
133-155 Waterloo Road
London SE1 8UG
Our ref: 16/02/ld/2804
10 March 2021
Dear Mark Newman, Re: 2804 – FOI How many cycles are used in PCR testing in the UK
Thank you for your request received on 16 February 2021 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.
How many cycles are used in UK PCR Covid tests. Now and in 2020.
PHE can confirm it partly holds the information you have specified.
There is an extensive menu of tests currently used to detect SARS-CoV-2 in a
sample. Whilst most of these tests are PCR based, there are also assays that use
alternative technology for the detection of SARS-CoV-2 nucleic acid.
Currently there are over 80 different testing platforms in use across the various
networks of laboratories and the thresholds for result interpretation will be configured
in each case by the manufacturers of the assays and the instrumentation. Each
laboratory will regularly assess the performance of their assays within their local
quality management system. The results are monitored in accordance with defined
quality control procedures. Whilst each laboratory has a statutory duty to report
positive cases to Public Health England, additional information such as Ct values in
the case of PCR tests, is not submitted.
You may find the following document ‘Understanding cycle threshold (Ct) in SARS-
CoV-2 RT-PCR’ to be helpful. Please see the link below: https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attach
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.