Vaccinating to Protect a Vulnerable Subpopulation
The proportion of “vulnerable” (solid lines), and “core” (dashed lines) individuals infected as a function of the proportion of vaccine given to core individuals, for three different transmission scenarios. In low transmission, the value of R for core and vulnerable individuals is 2.0 and 1.2, respectively; in medium transmission R is 2.4 and 1.6; in high transmission R is 2.8 and 2.0. The overall proportion of the population vaccinated is 0.5. The vaccine is assumed to have an efficacy of 80% in protecting core individuals and 50% in protecting vulnerable individuals. The two subpopulations are assumed to be of equal size. The coefficient of preferred mixing used is 0.7 (see Methods).