Figure 4
Vaccination ratio of the population of Japan calculated as \(R_{V}(t)\) = (number of vaccinations in Japan up to date t)/2(Japanese population). The first vaccination day is shown. A sigmoid-like function \(R_{V}^{\infty } S(\gamma _{V}(t-t_{V}))\) fits the data, and the parameters are \(t_{V}=590\), \(\gamma _{V}^{-1}=34.6\), and \(R_{V}^{\infty }=0.817\).
