  As infectious disease outbreaks emerge, public health agencies often enact
vaccination and social distancing measures to slow transmission. Their success
depends on not only strategies and resources, but also public adherence.
Individual willingness to take precautions may be influenced by global factors,
such as news media, or local factors, such as infected family members or
friends. Here, we compare three modes of epidemiological decision-making in the
midst of a growing outbreak. Individuals decide whether to adopt a recommended
intervention based on overall disease prevalence, the proportion of social
contacts infected, or the number of social contacts infected. While all
strategies can substantially mitigate transmission, vaccinating (or self
isolating) based on the number of infected acquaintances is expected to achieve
the greatest herd immunity and number of infections averted, while requiring
the fewest intervention resources.
