Something extremely bogus is going on. Was tested for covid four times today. Two tests came back negative, two came back positive. Same machine, same test, same nurse. Rapid antigen test from BD.
— Elon Musk (@elonmusk) November 13, 2020
Critics of the Covid lockdown have been making the point for some weeks now that it might be worth investing the time to find out whether it might be the case that the current covid tests are simply too sensitive, and are returning vast numbers of false positives.
When this issue was raised in Ireland in late September, Government boffin Dr. Cillian DeGascun was fairly clear: Not really, he said:
Ireland’s coronavirus testing system delivers a maximum of one false positive for every 500 tests carried out, according to Dr Cillian De Gascun.
The Chair of Ireland’s COVID-19 Expert Advisory Group was speaking after officials announced 248 new confirmed cases and five further deaths.
In a Twitter thread earlier this month, Dr De Gascun noted that standard PCR tests can produce somewhere in the region of 1% to 3% false positive results – leading to claims Ireland could be wrongly diagnosing high numbers of people.
Speaking to On The Record With Gavan Reilly this morning, he said the tweet has, “kind of come back to it to bite me in some respects” and noted that when it comes to Ireland’s COVID-19 testing system, the highest possible percentage of false positives is 0.2%.
There is, obviously, a big difference between 0.2% and, in Elon Musk’s alleged case, 50%.
And indeed, DeGascun’s position is further weakened by data from the Lancet, which finds that in the UK, the false positivity rate could be anything from 0.8% to as high as… four per cent:
“The current rate of operational false-positive swab tests in the UK is unknown; preliminary estimates show it could be somewhere between 0·8% and 4·0%. This rate could translate into a significant proportion of false-positive results daily due to the current low prevalence of the virus in the UK population, adversely affecting the positive predictive value of the test.”
Here’s an important thing to understand about false positives: They are a proportion of the total tests conducted, not a proportion of covid cases. Some people instinctively hear “4% are false positives” and think “oh, that’s just four per cent of the cases”.
Not so. It’s four per cent of the tests (assuming the upper end of the lancet range).
So for example, if the false positivity rate were four per cent, and a country conducted 20,000 tests in a given day, then you would expect four per cent of twenty thousand to show up as Covid cases. Four per cent of twenty thousand is….. 800.
In other words, if the worst case scenario of false positives were to be happening, it would account for a huge portion of Ireland’s daily covid totals. A large number of asymptomatic cases, you say, after testing tens of thousands of people daily, while hospitalisation numbers and death numbers remain fairly flat?
Sounds like a case for Sherlock Holmes.
This isn’t some kooky far right theory, by the way. Here’s what the Lancet says:
“To summarise, false-positive COVID-19 swab test results might be increasingly likely in the current epidemiological climate in the UK, with substantial consequences at the personal, health system, and societal levels.”
There are a couple of questions here that the Irish public really should be asking:
- What reasons are there to believe that Dr. DeGascun is right that the false positivity rate is only 0.2%, when the Lancet says it could be as high as 4%?
- Given our high number of cases recently, but flat levels of hospitalisation and death, isn’t it very possible that we have a false positivity epidemic on our hands?
- Who is looking into this?
The lockdown is causing immense economic and societal harm. If there’s a chance the whole thing is founded on misleading data, then it’s time somebody investigated that.