Existence for Fractional SEIR Compartmental Model Involving Hilfer Fractional Derivative

In this paper, we research a type of newfashioned fractional models for COVID-19 outbreak, further improve it to Hilfer fractional mathematical models be called as SEIR compartmental models of order
$\alpha\in(0,1)$
and type
$\beta\in[0,1]$
on an unbounded domain
$[0,+\infty)$
. The existence for the nonlinear Hilfer fractional differential equations are proved via Schauder's fixed point theorem based on appropriate growth conditions in suitable Banach spaces. We conclude that the Hilfer fractional differential system has at least one solution in specified Banach space.