The flu" doesn't really describe a particular disease, but each year it's a different strain. If you're saying that at some point in everyone's life they'll get some viral infection, I think that's obvious, but that doesn't equate to saying that each year we should expect 100% (or anywhere close to it) will get that year's particular virus. — Hanover
That's exactly what I explain:
And if it keeps coming back like the flu where one part of the population has lost immunity due to a new strain, — boethius
Why it's considered the same disease is because it's phenomenologically similar, and descends fro the previous strains, just like you're considered the same person even if you cut your hair -- your different, but still the same person. A new strain that defeats immunity can be a small change like different hair for the virus; so it's considered the same disease, and the word "strain" is used to differentiate. That's why I used the word strain ... and also why you used the word strain in the same sentence as making the overall point that "it's actually a different disease".
The answer to whatever your'e trying to figure out will be found by looking at actual infection rates over time, not by whatever calculations you're throwing together. I can say that I've never been in a school or work situation where 70% of the people were gone due to the flu. — Hanover
Again, my comment explains why this is the case. Many people are immune to the new flu at any given time, and many others have so mild symptoms they think it's just a cold. So not everyone gets it any given year.
But take a new strain of highly infectious flu, such as happened in 1918, that no one seems immune to, and a high mortality rate relative the "normal flu" we have today, and the situation is very different.
My calculations are based on what we know so far.
- It's highly infectious
- No one has existing immunity to it
- It has demonstrated ability to kill of 0.5 - 1 % percent of cases in good care conditions, such as South Korea were infection rate was lowered to a manageable number, at least so far.
- It has demonstrated ability to kill 3 - 5 percent of cases in sub-optimal care conditions, such as Wuhan and Italy, were cases exceeded the medical systems ability to handle them.
- We do not know how many "mild" infections there are that don't result in cases, but the ice-burg hypothesis seems extremely unlikely at this time, as random sampling testing of the population has not revealed an iceberg of mild or asymptomatic cases, as is being done in Germany; there are some of these asymptomatic or super mild, but not close to twice as many, much less on the order of 10 times needed to significantly lower the danger and change policy to "it's not so bad guys", it is a few percent in this category.
Now, there can be lot's of infections that are in the incubation or first symptoms stage that have not moved yet towards cases and hospitalizations, but that is simply a time lag problem matching observations to the best model of what's going on requires estimating those infections and extrapolating critical care cases. However, in the "uncontrolled spread" scenario we don't care about current cases, just a ballpark estimate of infection to case ratio, and case fatality in triage conditions.
So, if left to go out of control, we could estimate 70% of people on the earth getting it this year, and if we conservatively estimate there's double undiagnosed and never diagnosed infections currently, so a 2.5% infection fatality that then matches up with 5% case fatality, then this is 120 million deaths this year.
I have not seen any data or analysis to suggest uncontrolled spread would far lower, such as 0.2%, than that estimate.
Of course, it's completely unfeasible to have an uncontrolled spread policy, so we're seeing extreme actions that will have a large affect on how things play out: these extreme actions are motivated to avoid this 70% infected, 1-5% infection fatality situation.