Figure 2.

Different combinations of the reproduction number (${\mathcal{R}}_0$), primary efficacy ($\eta$), baseline PASC probability ($\varphi$) and levels of immunity in the population are consistent with calibration targets when prevalence and total vaccine efficacy are known ($I^{*}=0.02$ and ${\text{VE}}_{\mathrm{T}}=0.8$). Calibration targets enforce constraints between the reproduction number (${\mathcal{R}}_0$) and primary efficacy ($\eta$) (a), and between the primary efficacy ($\eta$) and the baseline probability of developing PASC ($\varphi$) (b). Because of its role in controlling pathogen transmission, the primary efficacy ($\eta$) dictates the fraction of the population that is susceptible ($S/(S+P)$ versus $\eta$ (c)), with stronger immunity concentrating infections within susceptible individuals ($S/(S+(1-\eta )P)$ versus $\eta$ (d)). Other parameters: vaccination rate of susceptibles, $\alpha =1$ vaccine per year; mean duration of infection, ${\gamma }^{-1}=1$ week; mean duration of immunity, ${\delta }^{-1}=1$ year; fraction of infections developing PASC, $\mathcal{F}=0.05$.