Figure 4
From: Extracting key information from historical data to quantify the transmission dynamics of smallpox
Theoretical initial courses of smallpox outbreaks following a geometric growth. A. The infection tree (i.e. transmission network) of smallpox is shown by generation, following equation (8). For simplicity, R0 is assumed to be 2. B. Infection tree under vaccination. Vaccination is assumed to reduce the number of secondary transmission by 50%, and thus only 1 case in each generation is expected.