Num artigo genial publicado no Uncover DC, que um querido amigo partilhou comigo, Celia Farber expõe, como fracturas aberrantes, vários síndromas civilizacionais, entre a política e a ciência, que vêm a propósito do Covid-19. No momento central do artigo, ficamos a saber que a validade do teste de diagnóstico do C-19 é praticamente nenhuma, por muitas razões mas especialmente por esta: o critério de decisão entre um teste negativo ou positivo é completamente arbitrário, de tal forma que pode variar de laboratório para laboratório, de cidade para cidade, de país para país.
Recomendo a leitura do artigo, claro, mas se não tiverem paciência, reparem pelo menos neste absurdo:
"The first thing to know is that the test is not binary. In
fact, I don’t think there are any tests for infectious disease that are
positive or negative.
What they do is they take some kind of a continuum and they
arbitrarily say this point is the difference between positive and
negative.
PCR is really a manufacturing technique, (...) you start with a small amount of DNA and on each
cycle the amount doubles, which doesn’t sound like that much, but if
you double it 30 times, you get approximately a billion times more
material than you started with. So as a manufacturing technique, it’s
great. What they do is they attach a fluorescent molecule to the DNA as
they produce it. You shine a light at one wavelength, and you get a
response, you get light sent back at a different wavelength. So, they
measure the amount of light that comes back and that’s their surrogate
for how much DNA there is. (...) Basically, there’s a
certain number of cycles.
In one paper I found 37 cycles. If you didn’t get
enough fluorescence by 37 cycles, you are considered negative. In
another, paper, the cutoff was 36. Thirty-seven to 40 were considered
“indeterminate.” And if you got in that range, then you did more
testing. I’ve only seen two papers that described what the limit was.
So, it’s quite possible that different hospitals, different States,
Canada versus the US, Italy versus France are all using different cutoff
sensitivity standards of the Covid test. So, if you cut off at 20,
everybody would be negative. If you cut off a 50, you might have
everybody positive.”
David Crowe . Canadian researcher, with a degree in biology and mathematics, host of The Infectious Myth podcast, and President of the think-tank Rethinking AIDS
