Smallpox vaccination and adverse reactions: guidance for clinicians.

Smallpox Vaccination and Adverse Reactions: Guidance for Clinicians The frequencies of smallpox vaccine-associated adverse events were identified in studies of the 1960s. Because of the unknown prevalence of risk factors among today's population, precise predictions of adverse reaction rates after smallpox vaccination are unavailable. The majority of adverse events are minor, but the less-frequent serious adverse reactions require immediate evaluation for diagnosis and treatment. Agents for treatment of certain vaccine-associated severe adverse reactions are vaccinia immune globulin (VIG), the first-line therapy, and cidofovir, the second-line therapy. These agents will be available under Investigational New Drug (IND) protocols from the Centers for Disease Control and Prevention (CDC) and the US Department of Defense. Smallpox vaccination in the preoutbreak setting is contraindicated for persons who have the following conditions or a close contact with the following conditions: (1) a history of atopic dermatitis, irrespective of disease severity or activity; (2) active acute, chronic, or exfoliative skin conditions that disrupt the epidermis; (3) pregnant women or women who desire to become pregnant in the 28 days after vaccination; and (4) persons who are immunocompromised as a result of HIV or AIDS, autoimmune conditions, cancer, radiation treatment, immunosuppressive medications, or other immunodeficiencies. Additional contraindications that apply only to vaccination candidates but do not include their close contacts are persons with smallpox vaccine-component allergies, women who are breastfeeding, those taking topical ocular steroid medications, those with moderate-to-severe intercurrent illness, and persons aged <18 years. In addition, history of Darier disease is a contraindication in a potential vaccinee and a contraindication if a household contact has active disease. In the event of a smallpox outbreak, outbreak-specific guidance will be disseminated by the CDC regarding populations to be vaccinated and specific contraindications to vaccination. Vaccinia can be transmitted from a vaccinee's unhealed vaccination site to other persons by close contact and can lead to the same adverse events as in the vaccinee. To avoid transmission of vaccinia virus (found in the smallpox vaccine) from vaccinees to their close contacts, vaccinees should wash their hands with warm soapy water or hand rubs containing ≥60% alcohol immediately after they touch their vaccination site or change their vaccination site bandages. Used bandages should be placed in sealed plastic bags and can be disposed of in household trash. Smallpox vaccine adverse reactions are diagnosed on the basis of clinical examination and history, and certain reactions can be managed by observation and supportive care. Adverse reactions that are usually self-limited include fever, headache, fatigue, myalgia, chills, local skin reactions, nonspecific rashes, erythema multiforme, lymphadenopathy, and pain at the vaccination site. Other reactions are most often diagnosed through a complete history and physical and might require additional therapies (e.g., VIG, a first-line therapy and cidofovir, a secondline therapy). Adverse reactions that might require further evaluation or therapy include inadvertent inoculation, generalized vaccinia (GV), eczema vaccinatum (EV), progressive vaccinia (PV), postvaccinial central nervous system disease, and fetal vaccinia. Inadvertent inoculation occurs when vaccinia virus is transferred from a vaccination site to a second location on the vaccinee or to a close contact. Usually, this condition is self-limited and no additional care is needed. Inoculations of the eye and eyelid require evaluation by an ophthalmologist and might require therapy with topical antiviral or antibacterial medications, VIG, or topical steroids. GV is characterized by a disseminated maculopapular or vesicular rash, frequently on an erythematous base, which usually occurs 6–9 days after first-time vaccination. This condition is usually self-limited and benign, although treatment with VIG might be required when the patient is systemically ill or found to have an underlying immunocompromising condition. Infection-control precautions should be used to prevent secondary transmission and nosocomial infection. EV occurs among persons with a history of atopic dermatitis, irrespective of disease severity or activity, and is a localized or generalized papular, vesicular, or pustular rash, which can occur anywhere on the body, with a predilection for areas of previous atopic dermatitis lesions. Patients with EV are often systemically ill and usually require VIG. Infection-control precautions should be used to prevent secondary transmission and nosocomial infection. PV is a rare, severe, and often fatal complication among persons with immunodeficiencies, characterized by painless progressive necrosis at the vaccination site with or without metastases to distant sites (e.g., skin, bones, and other viscera). This disease carries a high mortality rate, and management of PV should include aggressive therapy with VIG, intensive monitoring, and tertiary-level supportive care. Anecdotal experience suggests that, despite treatment with VIG, persons with cell-mediated immune deficits have a poorer prognosis than those with humoral deficits. Infection-control precautions should be used to prevent secondary transmission and nosocomial infection. Central nervous system disease, which includes postvaccinial encephalopathy (PVE) and postvaccinial encephalomyelitis (or encephalitis) (PVEM), occur after smallpox vaccination. PVE is most common among infants aged <12 months. Clinical symptoms of central nervous system disease indicate cerebral or cerebellar dysfunction with headache, fever, vomiting, altered mental status, lethargy, seizures, and coma. PVE and PVEM are not believed to be a result of replicating vaccinia virus and are diagnoses of exclusion. Although no specific therapy exists for PVE or PVEM, supportive care, anticonvulsants, and intensive care might be required. Fetal vaccinia, resulting from vaccinial transmission from mother to fetus, is a rare, but serious, complication of smallpox vaccination during pregnancy or shortly before conception. It is manifested by skin lesions and organ involvement and often results in fetal or neonatal death. No known reliable intrauterine diagnostic test is available to confirm fetal infection. Given the rarity of congenital vaccinia among live-born infants, vaccination during pregnancy should not ordinarily be a reason to consider termination of pregnancy. No known indication exists for routine, prophylactic use of VIG in an unintentionally vaccinated pregnant woman; however, VIG should not be withheld if a pregnant woman develops a condition where VIG is needed. Other less-common adverse events after smallpox vaccination have been reported to occur in temporal association with smallpox vaccination, but causality has not been established. Prophylactic treatment with VIG is not recommended for persons or close contacts with contraindications to smallpox vaccination who are inadvertently inoculated or exposed. These persons should be followed closely for early recognition of NEWS AND COMMENTS