On days 6-8 after their first-ever smallpox vaccination , 63 adult subjects were randomized to apply a self-adhesive bandage ( n = 20 ) , gauze with adhesive tape ( n = 21 ) , or gauze with a semipermeable dressing ( n = 22 ) over the vaccination site for a mean of 8 + / -2 h. Swabs from the external bandage surfaces and the vaccination sites were then assessed by real time vaccinia-specific polymerase chain reaction ( PCR ) in blinded fashion .
