Comparative efficacy of antiviral strategies targeting different stages of the viral life cycle: A viral quasispecies dynamics study*

While the COVID-19 pandemic continues, the use of antivirals provides hope for preventing and mitigating similar viral outbreaks. What is the comparative impact of different antiviral therapeutics? How do antivirals impact the viral load, i.e., the virus population in an individual’s bloodstream, in high and low-immunity individuals? We use a model of viral quasispecies dynamics to examine the efficacy of antiviral strategies targeting three critical aspects of the viral life cycle: fecundity, reproduction rate, or infection rate in individuals with varying degree of immunity [1]. We find a linear relationship between the viral load with the change in fecundity and a power law relationship with the change in the reproduction rate of the virus, with the viral load decreasing as the fecundity and the reproduction rates are decreased. Interestingly, however, for antivirals that target the infection rate, the viral load changes non-monotonically; the viral population initially increases and then decreases as the infection rate is decreased. The initial increase is especially pronounced for individuals with low immunity. We found that the therapeutics are only effective in such individuals if they stop the infection process entirely. Our results predict the effectiveness of different antiviral strategies for COVID-19 and similar viral diseases and provide insights into the susceptibility of individuals with low immunity to effects like long covid.

[1] https://doi.org/10.1101/2022.10.10.511620