Institute of Fundamental Technological Research

Viral infection in cell culture and tissue is modeled with delay reaction-diffusion
equations. It is shown that progression of viral infection can be characterized by
the viral replication number, time-dependent viral load, and the speed of infec-
tion spreading. These three characteristics are determined through the original
model parameters including the rates of cell infection and of virus production in
the infected cells. The clinical manifestations of viral infection, depending on tis-
sue damage, correlate with the speed of infection spreading, while the infectivity
of a respiratory infection depends on the viral load in the upper respiratory tract.
Parameter determination from the experiments on Delta and Omicron variants
allows the estimation of the infection spreading speed and viral load. Different
variants of the SARS-CoV-2 infection are compared confirming that Omicron
is more infectious and has less severe symptoms than Delta variant. Within the
same variant, spreading speed (symptoms) correlates with viral load allowing
prognosis of disease progression.

reaction-diffusion equations,spreading speed,SARS-CoV-2 variants,viral infection,viral load