1/ One point people miss about #Covid:

There are super-spreader events.
There are also super-TESTER events.

What do I mean?

Many people infected with #Sars-Cov-2 never have any symptoms at all. The commonly used figure is 40-50%, but the real percentage may be much higher...

2/ Why would I say that? The 40-50% figure is based on the general population with positive PCR tests. But antibody tests show those positive PCR tests hugely understate the number of people who have been infected and recovered. Those people presumably had no or mild symptoms...

3/ Because if they had they would have been tested.

On the other hand, when large groups of people in close quarters are PCR tested at once - prisoners or sailors or meatpacking workers, say - the tests regularly find 60-90% infectivity rates - BUT 90%+ asymptomatic rates.

4/ And last month's research out of Tokyo showed that even antibody tests might also UNDERSTATE the rates of infection at peak periods.

More evidence comes from hospitalizations this summer in the Sunbelt; Covid patients (including those admitted to the ICU) soared and fell...

5/ But OVERALL hospitalization and ICU rates changed far less. Sure, hospitals can control elective admissions, but ICU visits should not be fungible. But they were. What this suggests is that even among the population of ICU patients many people are WITH not FROM Covid...

6/ So the overall picture is that #sarscov2 is circulating widely - and can sometimes blow through a group (in a church, the West Wing, a frat house, wherever). But because so many infections are asymptomatic, we may miss not just individual cases but localized OUTBREAKS...

7/ Unless, that is, people are tested (because someone around them actually becomes ill, or their employer or school insists on testing).

If most people are asymptomatic, you can't have an epidemic without testing. That's why super-tester events are so important to the pandemia.