Contact transmission of vaccinia virus from smallpox vaccinees in the United States, 2003-2011

► We identified secondary and tertiary contact vaccinia cases that presented between December 2002 and March 2011. ► Cases were described in civilian or military adverse event reporting systems or peer-reviewed literature. ► One hundred fifteen cases of vaccinia transmission through contact were identified (5.4 per 100,000 vaccinees). ► Most cases were female household members or intimate contacts (n = 70, 60%) or wrestling partners (n = 18, 16%) of recent vaccinees. ► Contact vaccinia infections are infrequent and preventable through patient education and screening for contraindications to vaccination.