Before revision: It can be calculated analytically using the formula where r is the apparent infection rate t1 is the time of the first measurement t2 is the time of the second measurement x1 is the proportion of infection measured at time t1 x2 is the proportion of infection measured at time t2 The apparent infection rate is the average rate of increase of the log odds ratio of the infected proportion between the two measurement times.
After revision: It can be calculated analytically using the formula where r is the apparent infection rate t1 is the time of the first measurement t2 is the time of the second measurement x1 is the proportion of infection measured at time t1 x2 is the proportion of infection measured at time t2