April 14, 2020

expert comment about the reporting and publishing of COVID-19 test results

Comment about the reporting and publishing of COVID-19 test results.

Prof Sheila Bird, Formerly Programme Leader, MRC Biostatistics Unit, University of Cambridge, said:

“There are two main pillars of swab-testing (the have I got it test).

“Pillar 1 is swab testing in Public Health England laboratories and NHS hospitals for those with a medical need (1a); and for the most critical workers and their families/household-members (1b). Pillar 2 is swab testing for key workers and their households.  In Pillar 2, number of tests equals number of persons tested, and the positive-rate was 32% (799 positives out of 2 489 persons tested).

“See table below for the most recently-reported swab-tests for coronavirus-2 (on 12^th and 13^th April): number of tests, numbers of persons tested and numbers positive.  I assume that means number of persons who tested positive*.

“Ten truths behind the pillar are answers to 10 obvious questions:

1. How many Pillar 1 swab-tests, persons tested and positives were on account of medical need (1a)?

2. What is the average number of tests per person when testing is on account of medical need (Pillar 1a)?

3. What is the positive-rate for persons who are tested on account of medical need (Pillar 1a)?

4. How many Pillar 1 swab-tests, persons tested and positives were for our most critical workers and their families/household members (1b)?

5. What is the positive-rate for our most critical workers and their families/household members (Pillar 1b)?

6. As importantly, how many Pillar 1b swab-tests, persons tested and positives were for our most critical workers (Pillar 1b-CWs)?

7. What is the positive-rate (have I got it) for our most critical workers (Pillar 1b-CWs)?

8. As importantly, how many Pillar 2 swab-tests, persons tested and positives were for our key workers (Pillar 2-KWs)?

9. What is the positive-rate (have I got it) for our key workers (Pillar 2-KWs)?

“Most patients who are swab-tested on account of medical need have a follow-up swab-test: either because the patient initially tested negative for COVID-19 but clinicians consider the result may be a false-negative and so request a repeat-test or because the patient has recovered from COVID-19 and doctors want assurance that their patient is no longer infectious.  Hence:

10. What percentage of paired-swab-tests for the same patient in Pillar 1a are “1^st test negative, 2^nd test positive”; what percentage are “1^st test positive, 2^nd test negative”?

“Doctors deserve to know the answers to my 10 questions.  Other public health scientists who are tracking the pandemic cannot work optimally when key results for swab-testing are not all shared.  And the public has a right to a proper understanding of how data are collected, analysed and used to inform critical public policies.  The UK can surely do better.”

All our previous output on this subject can be seen at this weblink:

www.sciencemediacentre.org/tag/covid-19

Declared interests

None received.