There is a test for Covid-19 according to the BBC Radio 4 programme More or Less and it is based on the old saying …
If it walks like a duck, sounds like a duck and looks like a duck … it’s probably a duck.
What the radio programme delved into was the accuracy of the tests going on now for Covid-19. There are, it seems, some dodgy results.
We are getting false results since the amount of virus particles captured by swabbing may be too low to register in the test. First of all, this can be because swabbing both the back of the throat and nose can be a bit ‘iffy’, and secondly because the amount of virus in those of us who are infected varies over time, so the amount of virus particles captured by swabbing may be too low to register in the test.
The More or Less programme gave a typical figure for ‘someone has Covid-19 but tested as not having Covid-19’ (called false negatives in the jargon) of about 30%.
So as we move forward about 1 in 3 people tested will be told to be cautious and then start back into community life but may still have the infection.
Government advice has been that if you look like a Covid-19 Duck with your symptoms then it is best that you assume you are a Covid-19 Duck and self-isolate immediately and check your symptoms.
We have to ask, why tracing is based on test results that can come days after symptoms first appear and fall short of 100% accuracy, when, as the NCF propose, tracing can be automated much more and should start as though you had the virus the moment you start showing symptoms ?
The NCF has proposed to the Select Committee on Health and others that Covid-19 tracing apps are based on giving individuals their own Covid-19 contact information starting with contacts that have suspect, but not yet confirmed symptoms. That information should be on their smartphones to start with, and then perhaps on more devices over time as Singapore is doing.
If you let people know anonymously and automatically that they have been in contact with someone with suspect symptoms that allows the public to take early precautions in their own lives. NCF estimate that this should be 6-7 days earlier than the current test then trace working by the NHS. Time is critical in tracing activity and this could make a significant difference to the overall effectiveness of the whole system.
It is worth commenting on the range of symptoms that those with Covid-19 can display. They are many and various and it is quite possible that a person might display them due to something completely different. So the NCF approach may well result in people being notified with quite a number of false alarms from those who aren’t actually Covid-19 Ducks
(called in the jargon false positives).
So the NCF approach may be cautious but faster and thus safer, and people will learn from their own experiences and detailed contact information if and when suspects turn into confirmed Covid-19 contacts in a few days
We want to see the NCF guidance supported and strengthened with automated notification of suspect symptoms contacts that would enable people to look further back than 48 hours. People would then be better protected to keep overall levels of infection down and, as we have proposed, work better with local authorities.
Let’s get tracing all those Covid-19 Ducks!