Thread by @FrankfurtZack

Data is overwhelming – lockdowns don´t work.

But, why is that? The concept, in theory, is striking – if we reduce our contacts, we reduce viral spread. This is a no-brainer, isn´t it?

But then, why is data for lockdown so bad?

An important part of the answer in this Thread 👇

What is the concept behind the lockdown idea in detail?

It is based on the assumption that asymptomatic spread is a major contributor to the pandemic.

So lock up the people in their homes! This will stop asymptomatic transmission!

So far, so easy.

BUT: most data suggest that asymptomatic transmission is not a major driver of this pandemic.

Nobody knows the exact rate, but let's assume that one asymptomatic patient transmits the virus only to 0.5 Persons, as opposed to 3 Persons when symptomatic.

nature.com/articles/s4146…

So the chance of an asymptomatic person #1 infecting another asymptomatic person #2 is 0.5, the chance of person #2 infecting person #3 is 0.25, and so on.

In other words, the pandemic will stop by following the most simple NPI that is not very expensive:

isolate the ill ‼️

This is the most important, simple, but completely overlooked, and underrated NPI. Let´s call it rule #1.

Rule #1 is followed in every country, from Sweden to California, from South Dakota to Tanzania, from Cambodia to France.

Rule #1 is like a giant.

Any additional Social distancing that comes *on top* of rule #1 will only have minor or no impact, as it only applies to asymptomatic persons (or a few non-compliment individuals).

Rule #1 does not work perfectly, but additional lockdowns won´t change the course of the viral wave significantly.

Rules for healthy people simply don´t matter on an epidemiological scale.

Addendum: Is presymptomatic spread a major contribution? Probably not.

1. Time window for presymptomatic spread is short (Incubation -significant replication - symptoms)

2. Oligo-symptomatic individuals probably don´t spread the virus as effectively as someone with a cough.