CV and mad panic behaviour

[LP]

Isn't that a factor of herd immunity?

Less people who can get it means less people will get it.

R[sub]0[/sub] is the raw number with respect to natural immunity. If you put a hundred thousand people who had never been exposed to the virus into The G and dusted them with virus. It generally stabilises at some value like Influenza. It often starts high, presumably because there are a large number of tests for small number of infected.

R[sub]e[/sub] would take into account herd immunity, if you put a hundred thousand into The G some of which had been exposed and developed an immune response, and dusted them again! It diminishes as more immunity is found in the community and more mitigation steps are taken.

If a 100% effective vaccine is invented, R[sub]e[/sub] would go to zero, but R[sub]0[/sub] would stay some value because it's primarily a measure of transmission. A vaccine doesn't stop you being infected by a virus, it stops the virus you get infected with from doing you too much harm by priming the body's own defence system. Think of R[sub]e[/sub] as the number we work towards for any given R[sub]0[/sub].

On websites and media there is lots of cross pollination between R[sub]0[/sub] and other figures like R[sub]e[/sub], some of it by accident some of it not! I'm sure I'm even guilty myself of generalising to the term R[sub]0[/sub], but once you see R[sub]e[/sub] then you need to become more careful about the discussion because it is becoming specific to a frame of reference.

There was a good program on ABC national that put all this into lay terms a couple of months back. Much better at explaining it than myself, if I find it I'll post a link. When I sit listening to colleagues discuss this, as it has become the lunchtime topic of rigor, the jargon from the technical specialists is almost not navigable but they use it for brevity.