Fig 1.

Paths to population immunity through recovery from natural infection and vaccination.Population immunity as a combined function of fraction recovered (x) and fraction vaccinated (y). The heat map (with contours) denotes the estimated fraction of the population that is likely immune to severe infection (f = x + (1-x)*y). Contour lines denote equivalent levels of population level immunity, f. Vaccination initiatives that start with an estimated 30% of population recovered (estimated via serosurveys when accounting for seroreversion) reach 80% population level immunity given an intensive campaign (green; 2/3 vaccinated, 10% more infected); intermediate campaign (yellow; 1/2 vaccinated, 30% more infected), and an incomplete campaign (red; 1/4 vaccinated, 43% more infected). Estimated fatalities associated with start of vaccination campaign and after reaching target population level immunity, albeit with different coverage (fatalities are scaled with the increase in infected population for each scenario). A dashboard estimating population immunity amongst US states is available at https://popimmunity.biosci.gatech.edu. (For interpretation of the references to colour in their figure legend, the reader is referred to the web version of this article.)