Force of infection [λ(t)]

Rate of a susceptible host acquiring infection per unit time. Force of infection is also known as incidence or hazard rate and is often used in transmission dynamics models. Force of infection λ(t) is equal to β*c*I(t)/N(t), where β is the likelihood of infection transmission per contact, c is the contact rate, I(t)/N(t) is the prevalence of infection (I) in the total population (N) at time t.