Sensitivity and Specifity of the different PCR test are not only defined by different Ct values, but also different primers and gene loci make a big difference.
PCR is prone to contamination by very small amount of viral particles.
Hypothesis: we usually don't notice contamination, especially when it is happening *before* putting the probes into the PCR apparatus. This may even mimick a super spreader event.
Contamination of a reagent. Not discovered by the laboratory, but by the local health authority which was skeptical about the sudden increase in cases.
In 2017/18, Germany was faced with the deadliest flu season of the last 30 years. Nobody took notice. We missed it. @Markus_Soeder did not protect us. And we had plenty of toilet paper.
How much % is needed for #HerdImmunity? Not 60-70%, probably 10-20%. It depends on the variance in susceptibility - not everybody has the same risk to get infected. COVID takes the low-hangig fruits first.
Seasonality of #COVID is underappreciated. Most human viral disease occur in distinct cycles. This is especially true for respiratory infections. We don´t know the reason for this, but it´s NOT simply “the weather”.
Regular seasonal variance is the rule, not the exception!
