VIRUS HITTING CLOSE TO HOME
I highlighted the numbers below I’m referring to.
This is a very inaccurate number. It should not be used anywhere at any time. It means nothing. We do not know the death rate because likely millions currently have or have already had or are yet to have this virus, that haven't been or never will be tested. Therefore the percentage means nothing. It is very misleading.
FWIW.... I've been tracking the numbers closely since the 1st week of Feb. The mortality rate does indeed have meaning and is a worthwhile indicator relative to other pandemics. I'd suggest that looking at the US mortality rate alone will give you a lot more meaning than looking at the worldwide rate.
In the US the mortality rate started a bit higher than now, due the sudden outbreak in Washington state, particularly at the retirement home. It dropped quickly to around 1.5%, and then edged down to 1.3% about 2-3 weeks ago as testing in the US skyrocketed. But at that time, the big jump in cases in the NYC area started, and the jump in death rate about 7-10 days later was fully expected. And indeed it did, and now the US mortality rate has climbed back up to 2-2.5%. Every state where there has been a sustained infection for at least 2 weeks shows this mortality rate now.
I've seen plenty of claims that it has no meaning in comparison to seasonal flu mortality rates, as we do not know the total number of cases, including the asymptomatic cases (low or no symptom). This is not true.... the CDC's estimates on seasonal flu mortality is based on a similar metric. That figure is based on the ratio of deaths to estimated
symptomatic cases, and does not include asymptomatic cases of seasonal flu. So a 2+% mortality rate in the US can be reasonably compared to the average 0.1% seasonal flu rate to get an idea of how much worse this is. See here:
Estimated Influenza Illnesses, Medical visits, Hospitalizations, and Deaths in the United States — 2018–2019 influenza season | CDC
I have fund some papers and info relating to the total cases, that puts some general bounds on the ratio of asymtomatic to symptomatic cases for both seasonal flus, and for the Spanish flu. These numbers range from 2 to 4. So you could use those ratios to get some rough estimate of the probable total number of cases so far.
Getting a grip on the total is important for one reason: to get some idea when the herd immunity effect might start slowing the spread. That is based the total % of a society that has been infected and has built immunity. Once that total gets above the range of 10-15% of a population, then the herd immunity effect
starts to work in our favor, by starting to lower the spread rate. If we use the NYC area total infections as 3 times the NY state total, then that area is at about a 2% infected at this point in rough numbers. It will take about another 2.5-3 weeks for the % infected of the area population to reach 10%, if it holds at the present % rate of daily increase in infections. But 2-3 weeks is pretty long in terms of trying to do predictions on something changing this fast.
BTW.. the Spanish flu has more recently been estimated to have infected around 25% of the total world population. At that point, it died out.