Hammarlund E, Lewis MW, Hanifin JM, Simpson EL, Carlson NE, Slifka MK. Traditional smallpox vaccination with reduced risk of inadvertent contact spread by administration of povidone iodine ointment. Vaccine. 2008 Jan 17;26(3):430–9. PMID: 18083278; PMCID: PMC2323604.