I tried fitting a third order polynomial for JHU Covid data, just as a way to kill time. For all countries, the 95% confidence interval of the second derivatice

I tried fitting a third order polynomial for JHU Covid data, just as a way to kill time. For all countries, the 95% confidence interval of the second derivatice overlapped zero (i.e. it can't be estimated very well). We only have about three weeks of data from the 10th death, for most countries, you can't fit a very good curve with that.