Table 1.

Study subject characteristics.

Characteristic	Control (n = 17)	PIO (n = 18)
Age, average (range)	51 (38–58)	44 (33–59)
Number of vaccinations, average (range)	1.6 (1–6)	1.2 (1–2)
Years after last vaccination, average (range)	43 (32–56)	36 (17–50)
Male	12%	50%
Caucasian	88%	83%
Allergy/asthma	24%	33%

Table 1 contains the summary statistics of revaccinated subjects divided by treatment group on the medical information available on each subject. The PIO treatment group was significantly younger and therefore, the time from the previous vaccination was shorter (P = 0.02, 0.03, respectively). The two populations had a similar number of previous smallpox vaccinations (P = 0.22) and did not differ significantly by race (P > 0.99). The PIO treated group had a balance of males and females, while the untreated group was predominately female (P = 0.03). The total population was 91% non-smokers with 29% reporting allergies or asthma and these parameters did not differ between the two treatment groups (P > 0.71).