June 15, 2020

expert reaction to modelling preprint looking at health and economic impacts of TTI

A preprint, an unpublished non-peereviewed modelling study posted to GitHub, looked at health and economic impacts of Test Trace and Isolate (TTI) programmes. 

Dr Daniel Lawson, Lecturer in Statistical Science, University of Bristol, said:

“This is a brave attempt to put numbers on actions, and is at present the most comprehensive attempt for the UK.  It focusses on several scenarios for track and trace policies, accounting for cost of the policy, deaths, and the impact on economic activity.

“The paper paints a simplified picture of reality and should be viewed with caution, as epidemics are an exponential process so any mistake can be amplified.  For example, if an intervention proves less effective than assumed and the reproductive rate slides the wrong side of 1, then it might generate a second lockdown with economic consequences.  There are difficult trade-offs between these predictions and how they translate to real world risk.  The risk associated with each policy has not yet been considered.

“The modelling makes many assumptions that are unverified; for example the effectiveness of masks, the fatality rate, and the mortality time.  Further, it makes the assumption that contacts and economic impact are linearly related, which was not necessarily true in the past and certainly it is possible that they do not need to be into the future.  For example, we might hope that keeping office workers at home can reduce contacts without reducing economic output.

“Overall, this type of modelling needs to be followed by data-driven research to see whether the parameters chosen would reflect a good fit to what has been observed in this country, or others.  The value lies instead in asking, ‘what if track and trace worked like this?’, and it is all we have to address that question.  A comparison of different track and trace strategies is very valuable and should be fed into future statistical work.”

Preprint (not a paper): ‘Modelling the health and economic impacts of Population-wide Testing, contact Tracing and Isolation (PTTI) strategies for COVID-19 in the UK’ by Tim Colbourn et al.  This work is not peer-reviewed.

https://github.com/ptti/ptti/blob/master/docs/PTTI-Covid-19-UK.pdf

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

www.sciencemediacentre.org/tag/covid-19

Declared interests

None received.