Smallpox vaccine given years before 72% to 75% effective against mpox, data reveal

Researchers from Emory University and the Veterans Affairs (VA) Healthcare System conducted a retrospective, test-negative study involving 1,014 current and former military personnel with mpox symptoms tested for orthopoxvirus (eg, smallpox, cowpox, mpox) from July 1 to October 31, 2022. The researchers identified participants using Department of Defense electronic lab data and the VA Corporate Data Warehouse. From 2002 through 2017, more than 2.6 million military personnel received smallpox vaccinations (Dryvax, ACAM2000, or Jynneos, which is also approved for mpox) as part of their military deployment or occupational requirements. “During the ongoing global outbreak of mpox (formerly called monkeypox), smallpox vaccines have been used to prevent infection and reduce the severity of disease in those at increased risk for infection,” the study authors wrote. “However, the effectiveness of smallpox vaccines against mpox is unknown.” ACAM2000 may have slight edge over Dryvax A total of 184 participants (18%) had received a smallpox vaccine a median...