Posted: Fri Apr 17, 2020 11:44pm
SARS-CoV-19 is a NOVEL coronavirus - it's dangerous to assume that it behaves like other, known coronavirus.
As a new virus, scientists assume that EVERYONE is susceptible to infection. The reproduction rate, known as R0, determines the number of people infected by those who already have the infection. For example, in the early stages of what was known about the Covid-19 disease, the reproduction rate was estimated globally to be R2 to R3, i.e. for every person infected, they would pass the disease on to between 2 and 3 others, and each of those would pass it on to 2 or 3 others, and so on, resulting in the exponential infection rates we have been seeing in most countries. The best way to prevent this from happening is to stop people from infecting each other, i.e. isolation. Ultimately, the plan is to reduce R0 to a minus figure.
It's not possible to prove anything from the current stats, because of the different positions of each country on the infection curve and different approaches to intervention. I would argue that the UK, having had advance sight of the disease progression in other EU countries, should have moved quicker and harder; the USA has even less excuse for its slow response.
Also, we have recently learned that some countries have under-reported their death rates; just today, China has increased its death rate in Wuhan by 50% and the UK accepted that the figures from the ONS (Office of National Statistics) are a more accurate reflection of its death rate, because the ONS figures include deaths at care homes and private residences not included in the NHS figures.
I don't believe we will know for sure who "got it right" until the final analysis, which is a long way off; likewise, herd immunity or any level of immunity. The UK government changed its own strategy from (unproven) herd immunity to isolation, when modelling from Imperial College showed the huge numbers of people who would potentially have to die in the UK before the government could prove (or not) their 60% herd immunity theory.
One of the very few things we presently know for certain about the virus is that preventing infection by isolation saves lives.