Smallpox: What the Dermatologist Should Know

Phyllis I. Spuls, MD; Jan D. Bos, MD, PhD; Donald Rudikoff, MD


Skinmed. 2004;3(4) 

In This Article

Postvaccinial Central Nervous System Disease

Potential neurological complications of smallpox vaccination include postvaccinial encephalopathy, most common in infants <12 months of age, and postvaccinial encephalomyelitis (or encephalitis).[50] There were no identifiable predisposing factors for these reactions although the strain of vaccinia used may have affected incidence rates. The incidence was typically higher in Europe where the NYS-DOH vaccinia strain was not used. Postvaccinial encephalopathy, characterized by fever, headache, vomiting, drowsiness, lethargy, convulsions, and coma, occurred 6- 10 days after vaccination. Hemiplegia, aphasia, and transient amnesia resulted. Cerebral damage and hemiplegia could be permanent.

Postvaccinial encephalitis occurred in vaccinees over age 2 years and was characterized by the abrupt onset at 11-15 days after vaccination of fever, vomiting, headache, malaise, and anorexia.

These neurologic complications occurred at a rate of as few as three cases per million vaccinations[39] to as many as one case in 110,000 in the United States.[52] Approximately 15%- 25% of cases with postvaccination encephalitis died and an additional 25% had permanent neurological sequelae. There is no known effective treatment for postvaccination encephalitis and VIG is of no value once it has occurred. There are some data suggesting that VIG may have some value in prophylaxis of encephalitis.[53]

Vaccination can also cause erythema multiforme[36] and Stevens-Johnson syndrome.[38] Other complications of vaccination are categorized by organ system and include myocarditis, pericarditis, meningitis, and arthritis. There are rare reports of malignancies developing in vaccination scars.

VIG has proven efficacious in the prophylaxis and therapy of many but not all complications following smallpox vaccination. As previously mentioned, the recommended dosage of VIG for the treatment of adverse reactions (except postvaccination encephalitis and vaccinial keratitis) is 0.6 mL/kg body weight given by intramuscular injection. The dose is divided over a 24-36 hour period and may be repeated at 1-3 day intervals until no new lesions appear.[45]


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