  Social network analysis is now widely used to investigate the dynamics of
infectious disease spread from person to person. Vaccination dramatically
disrupts the disease transmission process on a contact network, and indeed,
sufficiently high vaccination rates can disrupt the process to such an extent
that disease transmission on the network is effectively halted. Here, we build
on mounting evidence that health behaviors - such as vaccination, and refusal
thereof - can spread through social networks through a process of complex
contagion that requires social reinforcement. Using network simulations that
model both the health behavior and the infectious disease spread, we find that
under otherwise identical conditions, the process by which the health behavior
spreads has a very strong effect on disease outbreak dynamics. This variability
in dynamics results from differences in the topology within susceptible
communities that arise during the health behavior spreading process, which in
turn depends on the topology of the overall social network. Our findings point
to the importance of health behavior spread in predicting and controlling
disease outbreaks.
