It sounds like you are assuming the virus spreads uniformly through the population. It does not.
The median age of the population isn’t as relevant as the prevalence of the virus within specific demographics in the population.
NYC may have a slightly smaller elderly population, but that won’t matter if the prevalence of the virus in their elderly population is, say, 2x higher than the national average.
I’ve only been following it loosely, but apparently NYC brought the virus into their nursing homes by discharging SARS-CoV-2 positive patients back into them, and the IFR in a nursing home is certainly not 0.2%.
The original comment is putting a bound on the case fatality rate by simplistically assuming everyone has been infected. The actual prevalence in nursing homes is irrelevant with that assumption. Nursing homes being prone to infection just tightens the bound.
The median age of the population isn’t as relevant as the prevalence of the virus within specific demographics in the population.
NYC may have a slightly smaller elderly population, but that won’t matter if the prevalence of the virus in their elderly population is, say, 2x higher than the national average.
I’ve only been following it loosely, but apparently NYC brought the virus into their nursing homes by discharging SARS-CoV-2 positive patients back into them, and the IFR in a nursing home is certainly not 0.2%.