Objective: To assess the optimal method for covering smallpox vaccination sites to prevent transmission of vaccinia.
Design: Randomized, nonblinded clinical trial.
Setting: Tertiary care medical center.
Participants: Vaccinia-naive and vaccinia-experienced volunteers.
Interventions: After vaccination, study participants were randomized to receive 1 of 3 types of bandage: gauze, occlusive with gauze lining, or foam. Vaccination sites were assessed every 3 to 5 days until the lesion healed. During each visit, specimens were obtained from the vaccination site, the bandage surface before removal, and the index finger contralateral to the vaccination site and were cultured for vaccinia. Time to lesion healing was assessed.
Results: All 48 vaccinia-naive and 47 (87%) of 54 vaccinia-experienced participants developed a vesicle or pustule at the injection site 6-11 days after vaccination. Fourteen (14%) of 102 participants had bandage cultures positive for vaccinia. All but 1 of these vaccinia-positive cultures were of a bandage from participants randomized to the gauze bandage group, and all but 3 were of bandages from vaccinia-naive participants. No finger-specimen cultures were positive for vaccinia. One episode of neck autoinoculation occurred in a vaccinia-naive individual who had vaccinia recovered from his gauze bandage on multiple visits. The foam bandage was associated with more local adverse effects (skin irritation and induration). The time to healing did not differ among the bandage groups.
Conclusions: The potential for transmission of vaccinia from a vaccination site is greater if the site is covered by gauze than if it is covered by occlusive or foam bandages. Use of an occlusive bandage with a gauze lining is the best choice for coverage of smallpox vaccination sites because of a reduced potential for vaccinia transmission and a lower reactogenicity rate. Bandage choice did not affect vaccination lesion healing.