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Review
. 2010 May 25:4:71-9.
doi: 10.2147/dddt.s3687.

ACAM2000: the new smallpox vaccine for United States Strategic National Stockpile

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Review

ACAM2000: the new smallpox vaccine for United States Strategic National Stockpile

Aysegul Nalca et al. Drug Des Devel Ther. .

Abstract

Smallpox was eradicated more than 30 years ago, but heightened concerns over bioterrorism have brought smallpox and smallpox vaccination back to the forefront. The previously licensed smallpox vaccine in the United States, Dryvax (Wyeth Laboratories, Inc.), was highly effective, but the supply was insufficient to vaccinate the entire current US population. Additionally, Dryvax had a questionable safety profile since it consisted of a pool of vaccinia virus strains with varying degrees of virulence, and was grown on the skin of calves, an outdated technique that poses an unnecessary risk of contamination. The US government has therefore recently supported development of an improved live vaccinia virus smallpox vaccine. This initiative has resulted in the development of ACAM2000 (Acambis, Inc.), a single plaque-purified vaccinia virus derivative of Dryvax, aseptically propagated in cell culture. Preclinical and clinical trials reported in 2008 demonstrated that ACAM2000 has comparable immunogenicity to that of Dryvax, and causes a similar frequency of adverse events. Furthermore, like Dryvax, ACAM2000 vaccination has been shown by careful cardiac screening to result in an unexpectedly high rate of myocarditis and pericarditis. ACAM2000 received US Food and Drug Administration (FDA) approval in August 2007, and replaced Dryvax for all smallpox vaccinations in February 2008. Currently, over 200 million doses of ACAM2000 have been produced for the US Strategic National Stockpile. This review of ACAM2000 addresses the production, characterization, clinical trials, and adverse events associated with this new smallpox vaccine.

Keywords: efficacy; safety; smallpox; vaccine; vaccinia; variola.

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Figures

Figure 1
Figure 1
Dryvax® consists of a mixed pool of vaccinia virus NYCBH strain. Six vaccinia virus clones were isolated and purified. These were all tested and Clone 2 (CL2) was found to have a virulence profile most closely resembling that of Dryvax®. This clone was propagated on MRC-5 cells and purified to produce the vaccine, named ACAM1000™. Additional expansion was carried out on Vero cells to produce more than 200 million vaccine doses, and the vaccine was renamed ACAM2000™. Abbreviation: NYCBH, New York City Board of Health.

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