Based on epidemiological data from the smallpox era, post-exposure vaccination is likely to be most efficacious whenadministered during the incubation period. As stated above, wehave chosen only to consider those models demonstrating incu-bation periods of more than 5 days that have also previouslybeen utilized to evaluate either pre- or post-exposure vaccina-tion. This selection criteria led to the exclusion of the Rabbitpox –New Zealand White Rabbits (aerosol) or Variola – cynomologousmacaque (intravenous) models due to short incubation periods[80–82]. The recently developed Calpox – marmoset (intranasal)[83,84] model shows promise for post-exposure vaccination mod-eling but was excluded from this review because no vaccine testinghas occurred in this model at this time.