“…While the general model from [13] was largely neglected until rather recently, most of the literature concentrating on the particular case of constant rates, there has been since the 1970s some papers considering age dependent epidemic models, see in particular [9]. More recently, several papers have introduced coupled PDE/ODE models for studying age of infection dependent both infectivity and recovery rate, see in particular [23,11,24,17,5] and chapter 13 in [18]. Since the beginning of the Covid-19 pandemic, a huge number of papers have been produced, with various models of the propagation of this disease.…”