Smallpox vaccination is not associated with infertility in a healthy young adult population

Concerns exist regarding reproductive health, including potential infertility, among young adults with military-related occupational exposures. This study evaluated infertility diagnoses in a large population of healthy young adults in relation to prior smallpox vaccination. Using a retrospective cohort design, the population consisted of United States military members eligible for smallpox vaccination in 2003-2004 who had electronic health care utilization records available through at least December 2005. Multivariable logistic regression models were applied to evaluate infertility among male and female populations separately. Among 253,973 men and 44,332 women included in these analyses, the adjusted odds of infertility diagnoses in those with prior smallpox vaccination were 0.94 [95% confidence interval (CI), 0.83-1.06] and 1.10 (95% CI, 0.94-1.28), respectively. Therefore, no association was found between smallpox vaccination and subsequent infertility diagnoses in either men or women. This study represents the first large epidemiologic investigation of infertility after the smallpox vaccine.