ACAM2000 smallpox vaccine

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ACAM2000 smallpox vaccine
Smallpox vaccination needle.jpg
Trade namesACAM2000
Other namesSmallpox (Vaccinia) vaccine live[1]
Clinical data
Main usesSmallpox, mpox[2]
Side effectsReactions at the site, swollen lymph nodes, fever, tiredness, myocarditis, pericarditis, encephalitis, vaccinia[3]
  • Potentially harmful[3]
Routes of
Pricking the skin[1]
External links
License data
Legal status

ACAM2000 is a smallpox vaccine to protect against smallpox and mpox (monkeypox).[2] A single dose is generally only used in those at high risk of disease.[2] It is given by pricking the skin of the upper arm several times with a 2-pronged needle which has been dipped in the vaccine.[1] Similar vaccines have been used in all age groups.[3] A booster dose may be given every three to ten years in those with continuing high risk.[2]

Common side effects include reactions at the site it was given, swollen lymph nodes, fever, and tiredness.[3] Other side effects may include myocarditis, pericarditis, encephalitis, and vaccinia.[3] While use in pregnancy may harm the baby, such use may be warranted after exposure to smallpox.[3] It contains live vaccinia virus which can spread to close contacts.[3]

ACAM2000 was approved for medical use in the United States in 2007.[4] By 2008, it replaced Dryvax, the prior vaccine of choice for preventing smallpox.[5] It is manufactured by Emergent Product Development Gaithersburg and made in cell culture.[4][6] In 2008 it costs governments about 5 USD per dose.[7]

Medical uses

The vaccine provides protection against smallpox and is used in people at high risk for smallpox infection.[8]

Smallpox is considered a biological threat. Biological agents are toxins or organisms that can cause illness or death in humans, animals and plants. Exposure can come from an intentional biological terrorist attack, accidental release of the agent, or a natural accident.[9]

Smallpox last occured in 1977; however, there is interest in the development of vaccines due to the possible use of smallpox as a bioweapon.[10]


The vaccine is giving using a bifurcated stainless steel needle, and must never be administered by intradermal, subcutaneous, intramuscular, or intravenous routes.[2] The needle is dipped into the vaccine solution and used to prick the skin several times in the upper arm.[2] The vaccinia virus will begin to grow at the injection site.[2] It will cause a localized infection, with a red itchy sore produced at the vaccination site within three to four days.[2] If the infection occurs, that is an indication that the vaccine was successful.[2] Ultimately, the sore turns into a blister and then dries up.[2] A scab forms and then falls off in the third week, leaving a small scar behind.[11] Where possible, other vaccines should be delayed and live vaccines should be given with a separation of 28 days.[2] If due a COVID-19 vaccine (Moderna, Novavax, or Pfizer-BioNTech) or a tuberculin skin test for tuberculosis, then it should wait for at least one month after the ACAM2000 vaccine.[2] However, the ACAM2000 vaccine may be given following those COVID-19 vaccines without having to wait.[2] If multiple injections are necessary, they should separated by at least one inch or given in different limbs.[2]

Side effects

Most people who have taken the vaccine have mild reactions such as a sore arm, fever, and body aches. Some may have side effects ranging from serious to life-threatening.[12] Common side effects include inoculation site symptoms, lymphadenitis, and malaise, fatigue, fever, myalgia, and headache."[13] These reactions are less frequent in people being revaccinated than those receiving the vaccine for the first time.[13]

The ACAM2000 vaccine cannot cause smallpox because it does not contain the smallpox virus.[11]

Those who have been vaccinated may be able to spread the vaccinia virus to other people via direct contact for up to three weeks and thus it is recommended that they avoid people who are at high risk.[3]


The vaccine can be given to pregnant women who have been exposed to smallpox if MVA-BN is not available. No contraindications exist to receiving the vaccine in case of an outbreak emergency. "Because the risk of maternal serious illness or death, prematurity, miscarriage, or stillbirth from a smallpox infection are greater than the risk of the vaccination, smallpox vaccine is recommended and should be offered to pregnant women in case of an outbreak emergency."[14]



First-generation vaccines were derived from calf-lymph, and include Dryvax, APVS, Lancy-vaxina and Lister. Second-generation vaccines are cell-cultured and include ACAM2000 and CCSV.[10]

Both Dryvax and ACA2000 come from the New York City Board of Health strain of vaccinia. Dryvax was grown on calf skin and then freeze-dried for storage. Dryvax was first licensed by the FDA in 1931; however, it is no longer manufactured. ACAM2000 is a second generation smallpox vaccine. It comes from a clone of Dryvax which is purified and produced using modern cell culture technology.[11]

Emergent BioSolutions developed ACAM2000 under a contract with the U.S. Centers for Disease Control and Prevention (CDC).[15]

The U.S. Food and Drug Administration (FDA) approved ACAM2000 in August 2007. By February 2008, it replaced Dryvax for all smallpox vaccinations.[16]

Society and culture

As of 2010, there were over 200 million doses manufactured for the U.S. Strategic National Stockpile.[16] According to the U.S. FDA, "The approval and availability of this second-generation smallpox vaccine in the Strategic National Stockpile (SNS) enhances the emergency preparedness of the United States against the use of smallpox as a dangerous biological weapon."[11]


  1. 1.0 1.1 1.2 "ACAM2000 (Smallpox Vaccine) Questions and Answers". FDA. Center for Biologics Evaluation and Research. 23 March 2018. Archived from the original on 20 May 2022. Retrieved 20 May 2022.
  2. 2.00 2.01 2.02 2.03 2.04 2.05 2.06 2.07 2.08 2.09 2.10 2.11 2.12 2.13 "Mpox in the U.S." Centers for Disease Control and Prevention. 21 October 2022. Archived from the original on 29 November 2022. Retrieved 4 December 2022.
  3. 3.0 3.1 3.2 3.3 3.4 3.5 3.6 3.7 "Smallpox Vaccine Live Monograph for Professionals". Archived from the original on 1 June 2022. Retrieved 8 August 2022.
  4. 4.0 4.1 Remington, Jack S.; Wilson, Christopher B.; Nizet, Victor; Klein, Jerome O.; Maldonado, Yvonne (27 August 2010). Infectious Diseases of the Fetus and Newborn E-Book. Elsevier Health Sciences. p. 904. ISBN 978-1-4377-3637-3. Archived from the original on 12 August 2022. Retrieved 8 August 2022.
  5. Saleh, Amr; Qamar, Shahraz; Tekin, Aysun; Singh, Romil; Kashyap, Rahul (July 2021). "Vaccine Development Throughout History". Cureus. 13 (7): e16635. doi:10.7759/cureus.16635. ISSN 2168-8184. PMID 34462676. Archived from the original on 21 May 2022. Retrieved 21 May 2022.
  6. Bonville, Cynthia; Domachowske, Joseph (2021). "28. Smallpox". In Domachowske, Joseph; Suryadevara, Manika (eds.). Vaccines: A Clinical Overview and Practical Guide. Switzerland: Springer. pp. 333–342. ISBN 978-3-030-58416-0. Archived from the original on 2 June 2022. Retrieved 1 June 2022.
  7. Lambert de Rouvroit, Axel; Heegaard, Erik D. (January 2016). "Total costs associated with replicating and non-replicating smallpox vaccines". Global Security: Health, Science and Policy. 1 (1): 3–9. doi:10.1080/23793406.2016.1171944.
  8. "Approved Products - ACAM2000". Archived from the original on 20 May 2022. Retrieved 8 September 2018.
  9. "Biological Threats". Emergent BioSolutions. Archived from the original on 14 August 2018. Retrieved 13 August 2018.
  10. 10.0 10.1 Metzger W, Mordmueller BG (2007). "Vaccines for preventing smallpox". Cochrane Database Syst Rev (3): CD004913. doi:10.1002/14651858.CD004913.pub2. PMC 6532594. PMID 17636779.
  11. 11.0 11.1 11.2 11.3 "Questions about Vaccines - ACAM2000 (Smallpox Vaccine) Questions and Answers". Archived from the original on 20 May 2022. Retrieved 8 September 2018.
  12. "Vaccine Safety | Smallpox | CDC". 13 July 2017. Archived from the original on 9 September 2018. Retrieved 8 September 2018.
  13. 13.0 13.1 "Highlights of Prescribing Information" (PDF). Archived (PDF) from the original on 9 September 2018. Retrieved 9 September 2018.
  14. "Smallpox vaccine Use During Pregnancy |". Archived from the original on 15 May 2021. Retrieved 8 September 2018.
  15. "About ACA2000" (PDF). Emergent BioSolutions. Archived (PDF) from the original on 14 August 2018. Retrieved 8 September 2018.
  16. 16.0 16.1 Nalca, A; Zumbrun, EE (25 May 2010). "ACAM2000: the new smallpox vaccine for United States Strategic National Stockpile". Drug Design, Development and Therapy. 4: 71–9. doi:10.2147/dddt.s3687. PMC 2880337. PMID 20531961.

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