Tested then told they’re infectious? Might well be true, if only symptomatic were being tested, but we all know they’re not.
We need to stop thinking of positive or negative but ’how positive’?
When somebody has tested positive previously (and at some time been infected), we have no simple and reliable way of distinguishing a repeat infection from non-viable, leftover RNA, although it is likely that somebody who actually has current infection – and who may be infectious to others – will have a much higher quantity of viral RNA on any swabs.
PCR tests work by repeatedly doubling the amount of genetic material in the original sample, until there is a detectable quantity of it. Each doubling is referred to as a “cycle”; and the number of cycles or doublings before there is a detectable quantity of genetic material is called the “cycle threshold” (CT or Ct). The larger the amount of viral RNA there is in the sample, the smaller the number of cycles that are required before it can be detected. And since the number of cycles is the CT value, the lower the CT value, the more virus there was in the original sample, and the more likely it is thought to be that the case was actually infectious, rather than still carrying leftover RNA, which is not clinically significant. Some of our labs do up to 47 cycles.....