  I discuss the so-called SuperSpreader epidemic, for which SARS is the
canonical examples (and, perhaps, MERS will be another). I use simulation by an
agent-based model as well as the mathematics of multi-type branching-processes
to illustrate how the SS epidemic differs from the more familiar uniform
epidemic (e.g., caused by influenza). The conclusions may surprise the reader:
(a) The SS epidemic must be described by at least two numbers, such as the mean
reproductive number (of "secondary" cases caused by a "primary case"), R0, and
the variance of same, call it V0; (b) Even if R0 > 1, if V0 >> R0 the
probability that an infection-chain caused by one primary case goes extinct
without intervention may be close to one (e.g., 0.97); (c) The SS epidemic may
have a long "kindling period" in which sporadic cases appear (transmitted from
some unknown host) and generate a cluster of cases, but the chains peter out,
perhaps generating a false sense of security that a pandemic will not occur;
(d) Interventions such as isolation (or contact-tracing and secondary case
isolation) may prove efficacious even without driving R0 below one; (e) The
efficacy of such interventions diminishes, but slowly, with increasing V0 at
fixed R0. From these considerations, I argue that the SS epidemic has dynamics
sufficiently distinct from the uniform case that efficacious public-health
interventions can be designed even in the absence of a vaccine or other form of
treatment.
