This seems very important. Our current strategy of widespread testing appears to be ignoring the fact that the PCR test has a non-zero false positive rate, which has major implications. In particular, at the moment it appears that *even with a positive test* it is more likely than not that you *don't* have the virus! This is really not good when serious decisions are being made based on the results of these tests.
Article in today's Telegraph (paywalled, sadly)
https://www.telegraph.co.uk/news/20...ns-coronavirus-pandemic-may-never-officially/
And this quote from Carl Heneghan from the Oxford CEBM, who as I've mentioned before has been one of the few people worth listening to throughout (his paper exposed the issue with the death figures last month, for example)
(Bold mine, in both quotes)
Article in today's Telegraph (paywalled, sadly)
https://www.telegraph.co.uk/news/20...ns-coronavirus-pandemic-may-never-officially/
...even at the most optimistic levels, false positives could be hugely skewing the current testing figures.
For example, take the current testing rates. Roughly 310,000 tests are being carried out each day at the moment and the Office for National Statistics (ONS) suggests there is a current community infection rate of 0.05 per cent.
That means that if testing was perfect, we should be picking up 155 positive cases a day and 309,854 negative cases.
Yet with the current false negative rates, we would miss 20 per cent of the positive cases, picking up just 124. More alarmingly, we would pick up 310 false positives, giving a total of 434 reported cases, nearly three times the real positive figure.
It also means that the probability of an individual with a positive test actually being infected would be around 28.5 per cent.
The anomaly also means that even if there was no virus in the community at all, we would never fall below 310 cases a day if we were testing at current levels.
And this quote from Carl Heneghan from the Oxford CEBM, who as I've mentioned before has been one of the few people worth listening to throughout (his paper exposed the issue with the death figures last month, for example)
“It does matter when your prevalence is very low. At this point if you have a positive test you are more likely not to be infected than to actually have the virus. Your chance of being infected is less than 30 per cent.
“The ONS currently cannot estimate prevalence because it does not now know what the false positive rate of PCR testing is.
“It looks like we’ll struggle to get out of this. We’re now in a spiral of bad data.”
(Bold mine, in both quotes)