Larger evidence base needed on residual immunity to smallpox, says new NIH study

Smallpox, eradicated globally in 1980, is on the cusp of a comeback thanks to advances in synthetic biology. Residual immunity in individuals who were previously vaccinated could mitigate the impact of a smallpox outbreak, but “a high degree of uncertainty” exists regarding the duration and degree of such partial immunity, according to the new report, “Evidence for Residual Immunity to Smallpox After Vaccination and Implications for Re-emergence,” published this month by the U.S. National Library of Medicine at the U.S. National Institutes of Health (NIH), which notes that there is a need to improve the evidence base for estimates on residual immunity to better inform planning and preparedness for re-emergent smallpox, including for first responders.