Vaccine Info

ACAM2000 Smallpox Vaccine

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Last reviewed
December 6, 2021
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ACAM2000 Smallpox Vaccine Description

ACAM2000 is a live vaccinia virus, a replication-competent vaccine, to protect against smallpox disease, the origin of smallpox is unknown. The ACAM2000 vaccine does not contain the variola virus and cannot cause smallpox. However, It includes the vaccinia virus, which belongs to the poxvirus disease family, genus Orthopoxvirus.

The Emergent BioSolutions Inc. replication-competent smallpox vaccine consists of a live, infectious vaccinia virus that can be transmitted from the vaccine recipient to unvaccinated persons who have close contact with the inoculation site or with exudate from the site. The vaccinia virus may cause rash, fever, and head and body aches. 

ACAM2000 vaccine is the primary smallpox vaccine designated for use in a bioterrorism emergency and forms most of the U.S. Government's smallpox vaccine stockpile. The U.S. Department of Health and Human Services awarded a contract to Emergent in September 2019 valued at approximately $2 billion over ten years for the continued supply of ACAM2000® into the U.S. Strategic National Stockpile.

ACAM2000 is approved for active immunization against smallpox disease for persons determined to be at high risk for smallpox infection. ACAM2000 is licensed in the U.S. by the Food and Drug Administration (FDA) (STN: BL 125158), and it was developed under a contract with the U.S. Centers for Disease Control and Prevention (CDC).

Approved in the U.S. in 2007, ACAM2000 Smallpox Vaccine is a live vaccinia virus derived from plaque purification cloning from Dryvax®, calf lymph vaccine, and grown in African Green Monkey kidney (Vero) cells and tested to be free of adventitious agents. ACAM2000 replaced Dryvax for all smallpox vaccinations in February 2008.

ACAM200 and JYNNEOS (Imvamune or Imvanex) are the two currently FDA licensed vaccines in the U.S. to prevent smallpox. JYNNEOS is also licensed specifically to prevent monkeypox.

Gaithersburg, Maryland-based Emergent BioSolutions (NYSE: EBS) is a global life sciences company whose mission is to protect and enhance life.

ACAM2000 Smallpox Vaccine Indication

ACAM2000 is indicated for active immunization against smallpox disease for persons determined to be at high risk for smallpox infection. Smallpox vaccines are no longer routine, although some soldiers and laboratory workers still are inoculated. The U.S. FDA published Questions about Smallpox and ACAM2000. Please read this Medication Guide before you receive a vaccination with ACAM2000. This Guide does not take the place of talking to your healthcare provider about ACAM2000 and the smallpox disease.

ACAM2000 Smallpox Vaccine Ingredients 

ACAM2000, developed by Acambis, is a second-generation lyophilized preparation of purified virus (grown in Vero cell line) in HEPES (hydroxyethylpiperazine ethanesulfonic acid)-buffered saline, pH 7.4, containing 1% to 4% human serum albumin USP, 5% mannitol, and trace amounts of antibiotics (100 U/mL polymyxin B and 100 µg/mL neomycin) (John Becher, RPh, CDC, personal communication, 2006). It must be reconstituted before use by the addition of a diluent.

ACAM2000 Smallpox Vaccine Dosage

ACAM2000 is administered as a single dose by the percutaneous route using the multiple punctures technique. The risk of side effects in household contacts is the same as those for the vaccine recipient. Therefore, the vaccination site requires special care to prevent the virus from spreading - Updated Medication Guide.

ACAM2000 Smallpox Vaccine Administration Risks

ACAM2000 is administered as a live virus preparation that is inoculated into the skin by pricking the skin surface. Following a successful inoculation, a lesion will develop at the site of the vaccination. The virus growing at the site of this inoculation lesion can be spread to other parts of the body or even to other people. Individuals who receive vaccination with ACAM2000 must take precautions to prevent the spread of the vaccine virus.

ACAM2000 is provided as a lyophilized preparation of purified live virus After reconstitution, each vial of ACAM2000 vaccine contains approximately 100 doses (0.0025 mL/dose). The concentration of vaccinia virus is 1.0-5.0 x 108 plaque-forming units (PFU)/mL or 2.5-12.5 x 105 PFU/dose determined by plaque assay in Vero cells. The product contains 2% albumin USP and trace amounts of neomycin sulfate and polymyxin B sulfate.

ACAM2000 Smallpox Vaccine Side Effects and Risks

Smallpox vaccine side effects were identified in 2010.

ACAM2000 Smallpox Vaccine News

November 18, 2021 - The U.S. CDC reported on November 15, 2021, the U.S. Government was notified of the report of a small number of intact, frozen vials labeled “smallpox” discovered by a laboratory worker while cleaning out a freezer in a facility that conducts vaccine research in Pennsylvania. The freezer facility was immediately secured and staff followed standard protocols for notifying CDC of such a potential discovery. The vials were sent securely to CDC for testing on November 18 to determine what they contained. No one was exposed to the contents of the vials.

November 4, 2021 - During an interview with the chair of the UK Health Select Committee Jeremy Hunt, Bill Gates warned that governments must prepare for future pandemics and smallpox terror attacks by investing billions in research and development.

November 4, 2021 - Emergent BioSolutions Inc. reported financial results for the third quarter ended September 30, 2021. The company reported ACAM2000 product revenues were $80.7m, as compared to $1m in 2020. Also received a contract modification to the 2016 AV7909 (Anthrax Vaccine Adsorbed with Adjuvant) development and procurement contract with the U.S. government, valued at approximately $399 million, to deliver doses of AV7909 to the Strategic National Stockpile (SNS) over 18 months.

February 19, 2021 - Emergent reported fourth-quarter 2020 earnings of $3.67 per share, improving from the year-ago quarter’s earnings of $1.57.

September 3, 2019 - Emergent BioSolutions Awarded 10-Year HHS Contract to Deliver ACAM2000 Into the Strategic National Stockpile. Robert G. Kramer Sr., president and chief executive officer of Emergent BioSolutions, stated, "Emergent applauds the U.S. government’s continued focus on national security demonstrated through its long-term stockpiling strategy, which ensures a sustainable supply of critical medical countermeasures such as ACAM2000 vaccine, and its investment in a stable domestic manufacturing infrastructure to help protect the U.S. population against smallpox in the event of an attack." 

June 21, 2019 - Emergent BioSolutions completes acquisition of ACAM2000® Business from Sanofi.

August 24, 2015 - U.S. FDA Risk Evaluation and Mitigation Strategy Release Letter - ACAM2000 - BLA 125158/58.

July 9, 2013 - Unintentional transfer of vaccinia virus associated with smallpox vaccines: ACAM2000 compared with Dryvax.

May 25, 20110 - ACAM2000™: The new smallpox vaccine for the United States Strategic National Stockpile.

April 17, 2008 - ACAM2000: a newly licensed cell culture-based live vaccinia smallpox vaccine. The studies with ACAM2000 indicate that it closely matches the safety of Dryvax in both non-clinical and clinical trials. ACAM2000 met two of the four primary surrogate efficacy endpoint criteria established for the Phase III clinical trials. Concern over the incidence of myopericarditis with ACAM2000 and Dryvax exists. So far the cardiac events seem to be self-limited.

ACAM2000 Smallpox Vaccine Clinical Trials

ACAM2000 Smallpox vaccine has been involved in various clinical trials.