Thread by @Axelisys

Graphs, Glorious Graphs!

As a simplification, pandemic spread needs 3 things

1. Infection rate - how likely infection is once exposed (per 100,000 people)

2. Death rate - Case Fatality Rate

3. Public health response & vaccination rate

#thread #COVIDー19 #CoronavirusOutbreak

https://twitter.com/WelshGasDoc/status/1232208118899257344

Different diseases have different profiles (eg Ebola is over "25 times" more deadly than Coronavirus). But the effect on a population is as much defined by a country's response to any outbreak, as viral spread. Slow public health lets cases breach herd immunity thresholds

In such cases, the herd immunity, whether natural or via vaccine, isn't enough to prevent new cases & raises lifetime probability of deaths from the disease dramatically. Combine that with greater vitality & outbreaks like #CoronavirusOutbreak get out of control

Marked in green on the below graph are the points when the public health response kicked in during each of swine flu & SARS.

(Original graph: Bianco Research)

We see the same with Ebola, until it transported itself across borders, into nations that didn't vaccinate nor have adequate disease control. Giving the disease a "second [and even third] wind"

(Source: WHO)

So far, we don't have enough data to state how well the public health response has been to #COVID19. We can definitely say it's worse than SARS 2003, but can't immediately say its better than Swine flu (yet). Albeit the virality is worse. Public health has yet to catch up

Looking back, the 2003 SARS outbreak originated in southern China & spread quickly due to the population density. This applies to cities like London & New York. Encountering more people, means more chance of infection in a day & speeds up propagation.

As an example, if your chance of infection is 8 out of 10 and you bump into 20 people who sneeze on or near you in 1 week, you're very likely to get it. If you are single and work at home & it takes you a month to meet 10 humans, you are very unlikely to catch it in any one week.

It might just pass you by altogether. It's why public health advice so far, includes "self isolation" for those experiencing flu like symptoms. While too late for them ď some who've contracted from them, it stops spreading new cases, which is necessary to stop the disease

Epilog
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What will be interesting is what happens when a vaccines launch & how effective the public health response has been to Coronavirus (#COVIDー19). It's only going to be possible to determine that in hindsight, even with deterministic "shapes" of the graphs, if not scale