“…with initial condition ๐ ๐ (๐, 0) = ๐ 0 ๐ (๐), ๐ ๐ธ (๐, 0) = ๐ 0 ๐ธ (๐), ๐ ๐ผ (๐, 0) = ๐ 0 ๐ผ (๐), ๐ ๐
(๐, 0) = ๐ 0 ๐
(๐) and ๐ ๐ท (๐, 0) = ๐ 0 ๐ท (๐). Compared to (49) we introduced the age dependent parameters: ๐(๐) โฅ 0, the transition rate of exposed individuals to the infected class, and ๐ผ(๐) โฅ 0, the disease-induced death rate of infectious individuals. The feedback control ๐ข ๐ in this case is defined as follows…”