What if you tweak the parameters of the exponent in your logistic function to make the curve more closely fit the data that’s coming in?
I don’t know exactly how you came up with those numbers, but obviously they entailed some educated guesswork. Adjusting these factors IN NO WAY invalidates your essential hypothesis—that this SARS coronavirus can be effectively modeled by a logistic function of the same form as other SARS.
The key questions remain:
1) What is the number of actual cases reached by the time the curve flattens?
2) When is this flattening achieved?
PS: Have you corrected your function for there probably being less gin & tonic consumed in America than the U.K.?