With smallpox remaining classified as a credible bioterrorism threat and mpox continuing to circulate globally, the United States has moved to shore up its medical countermeasure stockpile. The Administration for Strategic Preparedness and Response (ASPR), housed within the Department of Health and Human Services, has issued a contract modification worth approximately $52.7 million to Gaithersburg, Maryland-based Emergent BioSolutions for the supply of ACAM2000, a live vaccinia virus vaccine indicated for the prevention of both smallpox and mpox in high-risk individuals.
The modification falls under an existing 10-year contract between ASPR and Emergent (contract number 75A50119C00071). The procurement covers vaccine doses, ancillary supplies, and diluent replacement lots intended to support U.S. smallpox preparedness and response capacity. Deliveries are expected to begin in June 2026.
The award arrives as ACAM2000 is gaining traction in international markets. Saudi Arabia’s Food and Drug Authority recently approved the vaccine for immunization against smallpox and mpox in high-risk individuals, and Singapore’s Health Sciences Authority has expanded the vaccine’s approved indication to include mpox prevention in adults at high risk of infection. These regulatory milestones suggest growing allied-nation interest in vaccinia-based medical countermeasures.
Public health and national security experts have long identified smallpox as a potential bioterrorism agent given its high transmissibility and mortality rate. Maintaining a viable national stockpile of licensed countermeasures — including both vaccines and therapeutics — is a core pillar of U.S. biodefense strategy. The ASPR contract modification represents a continuation of that long-term investment.
ACAM2000 carries significant safety considerations that inform how and to whom it is administered. The vaccine is a replication-competent live virus and is contraindicated in individuals with severe immunodeficiency. Serious adverse events documented following vaccination include myocarditis, pericarditis, encephalitis, progressive vaccinia, eczema vaccinatum, and fetal death. Myocarditis and pericarditis have been observed in primary vaccinees at a rate of approximately 5.7 per 1,000. Because the live virus can be transmitted through close contact with a vaccinated person, risks extend beyond the vaccinee. These safety constraints mean that ACAM2000 is reserved for individuals determined to be at high risk, rather than used in broad population vaccination campaigns.
Emergent BioSolutions, which has supplied medical countermeasures to the U.S. government for more than 25 years, also holds contracts covering products directed at anthrax, botulism, and Ebola, among other threats.