Efficient vaccination strategies for epidemic control using network information

Background: Network-based interventions are most powerful against epidemics when the full network structure is known. However, resource constraints often require decisions based on partial network data. We investigated how the effectiveness of network-based vaccination schemes varied based on the accuracy of network data available. Methods: We simulated propagating an SIR process on static empirical social networks from 75 rural Indian villages. First, we used regression analysis to predict the percentage of individuals ever infected (cumulative incidence) based on village-level networks. Second, we simulated vaccinating 10% of each village at baseline, selecting vaccinees using 1 of 5 network-based approaches: at random (Random); random contacts of random individuals (Nomination); random high-degree individuals (High Degree); highest degree (Highest Degree); or most central (Central). The first three approaches require only sample data; the latter two require full network data. We also simulated imposing a limit on how many contacts an individual can nominate (Fixed Choice Design, FCD), which reduces data collection burden but generates only partially observed networks. Results: We found the mean and standard deviation of the degree distribution to strongly predict cumulative incidence. In simulations, Nomination reduced cumulative incidence by one-sixth compared to Random vaccination; full network methods reduced infection by two-thirds. High Degree had intermediate effectiveness. Somewhat surprisingly, FCD truncating individuals' degrees at three was as effective as using complete networks. Conclusions: Using even partial network information to prioritize vaccines at either the village or individual level substantially improved epidemic outcomes. Such approaches may be feasible and effective in outbreak settings, and full ascertainment of network structure may not be required.