Written Evidence Submitted by

Professor Sylvia Richardson CBE, Director, MRC Biostatistics Unit at Cambridge Institute of Public Health, University of Cambridge



After giving evidence, I listened to the next session of the Select Committee where Baroness Harding was answering questions on the T&T system. I was interested in hearing you mention our RSS statement on “how efficient statistical method can glean greater intelligence from Test, Trace and Isolate”  and ask Baroness Harding whether they were willing to consider our recommendations. The answers that she gave were inadequate in my opinion:


(i) getting record linkage sorted out so that automatically the system checks if any of the listed close contacts (either household or external) has a test during the quarantine period or shortly after that and is found positive should be done so that she could answer your question.

Apparently this is being implemented in Scotland. Such record linkage should not be difficult to do and to report on.  It would provide an good indicator to monitor as  a measure of efficacity of the T&T system for breaking chains of transmission;


(ii) the random sampling of household, visits and tests, that we recommend is not meant to tell people that they can break quarantine if the result is negative! By randomly sampling the day where the visit and the tests would be carried out, we would obtain important scientific information to understand the timing of transmission and the associated risk factors (including being able to study the influence of the threshold factor discussed by Prof Heneghan). Baroness Harding was reasoning at the individual level, whereas what we are proposing is collecting a well designed set of data to inform knowledge on transmission patterns and the associated risk factors. And as a by product, we would also have solid data on compliance with quarantine! At present, there is no published data on compliance to the best of my knowledge.


I do hope that the efficiency of gaining important knowledge on transmission patterns (and on % asymptomatic) using this high risk subset will find an echo in government at some point. I would be, of course, happy to pursue a discussion with you to try to achieve this.


Sylvia Richardson


(18 September 2020)