“…The SIRD system (2) represents a Markovian process where the previous states do not affect the current conditions, i.e., a memoryless SIRD system. Nevertheless, the network-like human interactions (including the COVID-19) evolve to a pattern with memory properties were past events impact recent events [19] , [20] , [21] , [22] , [23] , [24] , [25] , [26] , [27] . To cope with that, we apply the fractional-order calculus as a mechanism to represent the memory of the biological system since the fractional-order derivative operators represent more accurately the real phenomena in nature [17] , [18] .…”