Effective Reproduction Numbers
Four main epidemic periods were observed (in 2011, 2013, 2015, and 2016) and are described in detail in Figure 2 and Supplemental Table 3. The mean ascending phase of the epidemic periods were 7.7 weeks. Effective reproduction numbers ranged from 1.1 – 1.7 with a mean effective reproduction number of 1.3, depending on epidemic period and estimated serial interval (Fig 2B, Supplemental Table 3).