C : how to explain the higher CFR in Australia in wave 2 and the lower CFR in Europe,USA in wave 2
(compared to wave 2)
D : immunity may wane after 4 months (could also explain why we get a 2nd COVID-wave after 4 months -- if immunity plays a role despite only <10% infected)
how many % are infected in seasonal flu-waves ? 10% ? still it goes down. And immunity wanes , recently it has been recommended to get 2 shots per season for the elderly, Nov+Feb or such