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Review
. 2013 Jul;9(7):1489-96.
doi: 10.4161/hv.24319. Epub 2013 Apr 9.

Unintentional transfer of vaccinia virus associated with smallpox vaccines: ACAM2000(®) compared with Dryvax(®)

Danielle M Tack  1 , Kevin L Karem, Jay R Montgomery, Limone Collins, Marthe G Bryant-Genevier, Rosemary Tiernan, Maria Cano, Paige Lewis, Renata J M Engler, Inger K Damon, Mary G Reynolds
Affiliations
Review

Unintentional transfer of vaccinia virus associated with smallpox vaccines: ACAM2000(®) compared with Dryvax(®)

Danielle M Tack et al. Hum Vaccin Immunother. 2013 Jul.

Abstract

Background: Routine vaccination against smallpox (variola) ceased in the US in 1976. However, in 2002 limited coverage for military personnel and some healthcare workers was reinstituted. In March 2008, ACAM2000® replaced Dryvax® as the vaccine used in the United States against smallpox. Unintentional transfer of vaccinia virus from a vaccination site by autoinoculation or contact transmission, can have significant public health implications. We summarize unintentional virus transfer AEs associated with ACAM2000® since March 2008 and compare with Dryvax®.

Results: We identified 309 reports for ACAM2000® with skin or ocular involvement, of which 93 were autoinoculation cases and 20 were contact transmission cases. The rate for reported cases of autoinoculation was 20.6 per 100,000 vaccinations and for contact transmission was 4.4 per 100,000 vaccinations. Eighteen contact transmission cases could be attributed to contact during a sporting activity (45%) or intimate contact (45%). Of the 113 unintentional transfer cases, 6 met the case definition for ocular vaccinia. The most common locations for all autoinoculation and contact cases were arm/elbow/shoulder (35/113; 31%) and face (24/113; 21%). Methods We reviewed 753 reports associated with smallpox in the Vaccine Adverse Event Reporting System and CDC Poxvirus consultation log, reported from March 2008 to August 2010. Reports were classified into categories based upon standard case definitions.

Conclusion: Overall, unintentional transfer events for ACAM2000® and Dryvax® are similar. We recommend continued efforts to prevent transfer events and continuing education for healthcare providers focused on recognition of vaccinia lesions, proper sample collection, and laboratory testing to confirm diagnosis.

Keywords: Orthopoxvirus; adverse events; autoinoculation; contact vaccinia; smallpox vaccine; vaccinia virus.

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Figures

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Figure 1. ACAM2000® Blackbox warning.
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Figure 2. Case definitions adapted from the smallpox vaccine adverse reactions surveillance guidelines and Brighton Collaboration Vaccinia Virus Vaccine Adverse Events Working Group.aExamples include: erythema multiforme, urticaria, non-viral pustulosis, viral exanthem. bConjunctivitis: inflamed membrane that lines the inner surface of the eyelid and exposed surface of the eyeball excluding the cornea with serous or mucopurulent discharge and the presence of vesicles, ulcerations, or “moist appearing” white lesions. cBlepharitis: pustules, edema, hyperemia of eyelid +/− lymphadenopathy (periauricular or submandibular), cellulitis, fever. dPeriocular area: papules, vesicles or pustules above the brow or below the inferior occipital rim, but not involving adnexa, lids, lid margins or canthi
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Figure 3. Flow diagram illustrating selection, exclusion, and classification of VAERS reports that were reviewed as potential cases of unintentional transfer of vaccinia.
See this image and copyright information in PMC

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