Before revision:  In the first part, we have pointed out a major over-simplification, i.e., assumption of variation of the time derivatives of the variables with the linear  powers of the individual variables and introduced two new parameters to incorporate further non-linearity to the number of infected people in the model.
After revision:  In the first part, we have pointed out a major over-simplification, i.e., assumption of variation of the time derivatives of the variables with the linear powers of the individual variables and introduced two new parameters to incorporate further nonlinearity in the number of infected people in the model.