Modeling the infectious diseases concludes in systems of ordinary differential equations (ODEs). The compartments in these equations (e.g., the numbers of susceptible, infectious, or immunized individuals) change in time. The ODEs arriving in these models are quadratic. Thus, we may apply special type of Runge–Kutta (RK) pairs for solving them. Here, we construct a new RK pair of orders five and four that is special tuned for this type of ODEs. Its superiority over standard RK pairs from the literature is illustrated when applied to various epidemic models, valid in measuring COVID-19 spread.