Referee: 2

The author has addressed my previous comments in a satisfactory
manner. The manuscript can be published in its present form.

Referee: 1

I have carefully gone through the report of Referee#2 and the corrections
made in the manuscript in response to the comments of both the referees. I
feel that the manuscript has been upgraded significantly. In the new
version, the reinfection scheme has been modified and generalized. The
recovered individuals can now be reinfected either directly (with
rate gamma), or via susceptible phase (with rate gamma'). The SIRS
model corresponds to the case gamma=0, while the case gamma=gamma'=0
corresponds to the simple SIR model. Further, gamma' has been reduced
smoothly with respect to time. The diffusivity has also been varied. With
these inclusions, the theoretical model of the author now better explains
the rate of death in SARS-CoV-2 shown in Figure 1.

I have no further queries and recommend the manuscript for publication.