Figure 3.

Non-linearities in the dose response curve and probability of infection. Left: A representative function for a susceptible individual’s probability of infection p as a function of viral dose v for a single exposure event, together with the effective exposure , where f(v) is convex for all v, whereas p(v) is convex for sufficiently small v. The convexity of f(v) (which is demonstrated in Methods) yields an S-curve for p(v). Note that for any particular viral dose v, the effective exposure can vary from individual to individual. Right: A depiction of how the total effective exposure and the probability of eventually becoming infected scale with the number of exposure events. The total effective exposure is the sum of the effective exposures from each exposure event; see Methods for details.