Smallpox Adverse Reactions Cover Broad Range. (Mild Lesions Reassuring)

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CHICAGO -- With adverse reactions to smallpox vaccine making headlines and with more than 25,600 health care workers vaccinated so far, it's important for clinicians to understand and be able to recognize adverse reactions to the inoculation, said Dr. Christine G. Casey of the Centers for Disease Control and Prevention's National Immunization Program.

Because the smallpox vaccine is a live virus, mild reactions are common and more severe adverse reactions can occur, Dr. Casey said at the National Immunization Conference sponsored by the CDC. Based on recent adverse event reports, the CDC first recommended that civilian health care workers with known cardiac disease--such as cardiomyopathy, previous heart attack, history of angina, or other evidence of coronary artery disease--be temporarily deferred from receiving smallpox vaccination.

At the end of March, that policy was revised to include workers with at least three cardiac risk factors. Of the more than 25,600 civilian health care workers vaccinated from Jan. 24 through Mar. 21, the CDC has reported 17 cases of cardiac adverse events, including two deaths. Also, the Department of Defense has reported 10 cases of myopericarditis and one death among vaccinated services members.

Certain mild reactions are expected, such as fatigue, headache, myalgia, regional lymphadenopathy, fever, and at the vaccination site, pruritus, swelling, and erythema. Indeed, mild lesions of any type at the vaccination site are an indication that the vaccination was a take, Dr. Casey said. In a 2001 study of 680 first-time smallpox vaccinees, 50% reported fatigue, 40% headache, 20% muscle aches and chills, and 20% nausea. Pain at the injection site was reported by 86%, regional lymphadenopathy by 54%, and 10% had a fever of 100 [degrees] F or higher. Thirty percent reported feeling sufficiently ill that they had to miss work or school or had trouble sleeping (N. Eng. J. Med. 346[117]:1265-74, 2002).

In reactions that do not resolve, vaccinia immune globulin (VIG) is the preferred treatment, Dr. Casey said. Cidofovir often is used as a second-line treatment, though its efficacy has not been proven.

According to results from past studies, Dr. Casey said, the most frequent adverse reactions and their symptoms are:

* Inadvertent inoculation. This most common reaction is usually spread from the vaccination site to another site on the body or to a close contact. The eyes, face, nose, mouth, genitalia, and rectum are commonly affected; resultant lesions typically follow the vaccination course. Frequent hand washing is the best prevention, Dr. Casey said. The reaction usually resolves itself in less than 3 weeks, though VIG could be indicated in cases of severe or extensive manifestation.

* Nonspecific rash. Flat, erythematous macules or patches can appear about 10 days after vaccination that usually resolve spontaneously in 2-4 days.

* Erythema multiforme. Lesions typically include macules, papules, wheals, and bull's-eyes. Onset is about 10 days after vaccination. Antipruritics are indicated, but VIG is not.

* Ocular vaccinia. Patients may present with blepharitis, conjunctivitis, keratitis, iritis, or a combination. They should be treated in consultation with an ophthalmologist, who might use topical antivirals, topical steroids, topical antibacterials, or systemic VIG.

* Generalized vaccinia. Vesicles or pustules may appear on normal skin distant from the vaccination site, usually 6-9 days after vaccination, and often be accompanied by fever, headache, and myalgia. …