Focal and Generalized Folliculitis Following Smallpox Vaccination Among Vaccinia-Naive Recipients

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Abstract
Context With the reintroduction of smallpox vaccination, detailed contemporary descriptions of adverse reactions to the vaccine are needed to adequately inform the public and clinicians. During a multicenter, randomized controlled trial investigating the efficacy of various dilutions of smallpox vaccine, we observed the appearance of a papulovesicular eruption (focal and generalized) in study volunteers. Objective To characterize the papulovesicular eruptions by clinical, virologic, and histopathological characteristics. Design, Setting, and Participants Prospective case series of papulovesicular eruptions following smallpox vaccination in healthy, vaccinia-naive adult participants compared with noncases conducted from October 2002 to March 2003. Variables potentially related to these eruptions were collected retrospectively through chart review. Eruptions were described based on viral culture, clinical examination, and histopathological evaluation (1 biopsy specimen from 1 case). Main Outcome Measure Cases of papulovesicular eruptions following vaccination. Results During the trial, of 148 volunteers (56% women; mean age 23.6 years), 4 participants (2.7%) developed generalized eruptions and 11 (7.4%) noted focal eruptions. Viral cultures of sample lesions were negative for vaccinia. The result of a skin biopsy sample from 1 case of generalized rash revealed suppurative folliculitis without evidence of viral infection. All lesions resolved without scarring. In the cohort, cases and noncases did not show significant differences in terms of sex, in the use of nonsteroidal anti-inflammatory drugs or oral or depo contraceptives, in medication allergies, in the incidence of fever or lymphadenopathy after vaccination, or in the dilution of vaccine received. Conclusions Folliculitis is a common and benign eruption observed in vaccinia-naive adult volunteers following smallpox vaccination. This eruption may be seen in volunteers receiving the vaccine in the newly instituted vaccination programs and may be met with heightened anxiety, potentially being confused with generalized vaccinia. This description of folliculitis using clinical, virologic, and histopathological findings should allay these concerns and provide additional insight into this eruption.
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