with three doses of vaccination using Caputo–Fabrizio fractional derivative (CFFD). The
presented solution is based on Laplace transform with Adomian decomposition method
(LADM), which is an effective technique to obtain a solution for such type of problems. Our
solution involves nonlinear differential equations of fractional order (FODEs) with non-
singular kernel. Also, we provide analysis to verify the existence of a solution to the …