  We investigate the Susceptible-Infectious-Recovered contagion dynamics in a
system of self-propelled particles with polar alignment. Using agent-based
simulations, we show that the emerging spatial features strongly affect the
contagion process, in addition to standard epidemic parameters given by the
base reproduction number and duration of the individual infectious period. We
find that the ordered homogeneous strongly disfavor the infection propagation,
due to their limited mixing, and only propagate contagion for very high
individual infectious periods. The disordered homogeneous states also display
low contagion capabilities, requiring relatively high infection parameters to
propagate the infection. Instead, the ordered inhomogeneous states display high
contagion for a range of parameter values. In these states, the formation of
bands and clusters favors contagion through a combination of processes that
develop within and without these structures. Our results highlight the
importance of the self-organized spatial dynamics in contagion processes, with
implications for understanding of contagion process and its control in
self-organized animal groups and human crowds.
