The patterns of propagation of the severe acute respiratory syndrome (SARS) outbreak of 2003 were not explained by conventional epidemic models that assumed homogeneity of infectiousness. Instead, the existing datasets were best matched by models that used negative binomial distributions, in which a small proportion of cases were highly infectious (Lloyd-Smith et al., 2005; McDonald et al., 2004; Shen et al., 2004). Data and modelling supported the existence of superspreaders, which played a crucial role in propagating the disease by being very efficient at transmitting SARS-CoV-1, such that in the absence of superspreading events most cases infected few, if any, secondary contacts (Stein, 2011).
