Multi-strain models

Multi-strain models represent two or more pathogen variants or strains that circulate in the same host population.

Why strains must be distinguished

Strains may differ in transmissibility, infectious duration, disease severity, immune escape or response to interventions.

Interactions between strains

Previous infection with one strain may provide complete, partial or no protection against another. Strains can therefore compete for susceptible hosts or coexist through incomplete cross-immunity.

Model structure

Separate infected compartments can be introduced for each strain, together with appropriate susceptibility and immunity states. More detailed models may also represent coinfection or sequential infection.