Trajectories of vaccination coverage achieved at the island-wide level during modeled vaccination campaigns and in relation to levels of coverage required for herd immunity.
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Abstract
<p>Three types of coverage are referred to in the text: target coverage achieved in the subset of the population at the time and location of a local campaign (i.e. within a block); island-wide vaccination coverage (y-axis); and critical vaccination coverage (<i>P<sub>crit</sub></i>) which is required for herd immunity and is determined by <i>R</i><sub>0</sub>, the basic reproductive number of rabies in Bali, <i>P<sub>crit</sub></i> = 1-(1/<i>R</i><sub>0</sub>). <i>R</i><sub>0</sub> estimated for Bali is 1·2, which corresponds to a <i>P<sub>crit</sub></i> of 17% (grey solid line). A 40% coverage campaign resulted in a trajectory that stayed above 17% (black solid line) and the probability of eradication was 1 (<a href="http://www.plosntds.org/article/info:doi/10.1371/journal.pntd.0002372#pntd-0002372-g003" target="_blank">Fig. 3B</a>), whereas 30% coverage resulted in a trajectory that dipped below 17% (black dashed line) and the probability of eradication was less than 1 (<a href="http://www.plosntds.org/article/info:doi/10.1371/journal.pntd.0002372#pntd-0002372-g003" target="_blank">Fig. 3B</a>). Annual campaigns were modeled, using parameters in <a href="http://www.plosntds.org/article/info:doi/10.1371/journal.pntd.0002372#pntd-0002372-t001" target="_blank">Table 1</a> and the ‘random’ six-month strategy (<a href="http://www.plosntds.org/article/info:doi/10.1371/journal.pntd.0002372#pntd-0002372-t002" target="_blank">Table 2</a>). Blocks are assumed to be vaccinated at the end of the month hence coverage increments jaggedly. Coverage declines between vaccinations due to waning of immunity and dog population turnover.</p
