15740 deaths ÷ 2700000 infected = 0.58% (they round to 0.5%)
However they note that the official state death count (15740 deaths) «only indicates deaths that happened in a hospital or a nursing home, and does not include coronavirus-related deaths that occurred in a home, which means the official death count is likely higher than that official number»
The true number of deaths, including home deaths, is 20759 as of the date of Cuomo's press briefing, April 24 (source: https://raw.githubusercontent.com/nytimes/covid-19-data/mast...)
Furthermore, all the figures quoted by Cuomo were provisional, mid-study. The serosurvey actually completed on April 28 and was published here: https://www.medrxiv.org/content/10.1101/2020.05.25.20113050v... The final figures as of this date were:
22777 deaths ÷ (19450000 state population × 14.0% infected) = IFR of 0.84%
It is important to take deaths as of April 28 in order to minimize right censoring.
«Both the UK and NY State had a policy of sending recovering patients to nursing home»
Spain and Brazil did not do this and still exhibit an IFR of 1% add per the serosurveys I referenced.
Isn't the death rate the percentage of population that dies when all are infected? Then nothing can be "exacerbated" by that alone? It then just reflects the death rate which results from the people being infected, no matter the speed?
To get the rate one can indeed calculate it with smaller representative sample, but that just doesn't imply that the vulnerable people would somehow never become infected if the epidemic continues, so the deaths of the old can't be avoided then. That the old die much more is a fact, and nothing that by itself "exacerbates" the rate.
Edit: I haven't seen any argument that estimated more than 20% of NY population that were supposedly infected were somehow specially skewed sample to hit only old people, and I'd argue that if the sample is that big it's quite improbable. If the argument is that the virus got faster in the nursing homes, one can also argue that all the old people outside of nursing homes skewed in the another direction by managing to initially not get the infection, but that as epidemic progresses they would indeed eventually become infected and suffer.
Edit2: "the virus is rather showing signs of going away" claim is very curious to me. I don't see it "going away" looking at all the statistics across the different parts of the world. I see only the slowdown of the spread, which corresponds to people generally changing their behavior to slow it down.
If it is the case, you don't expect the same death rate to scale up as the wider population continues to get infected (if it is still happening, the virus is rather showing signs of going away).
I am also starting to hear some noise that there might be cross immunity between this virus and previous coronavirus. In a recent video Prof Raoult was suggesting it might explain the low infection rate of people under 20 [1]. I am not qualified to tell whether the theory has any leg but it may be that we underestimate the spread of the virus when looking at a specific antibody.
[1] https://www.youtube.com/watch?time_continue=734&v=zUbiYhknaK... (in french)