This report outlines recommendations for the clinical use of the three
smallpox vaccines stored in the U.S. Strategic National Stockpile for persons who are exposed to smallpox virus or at high risk for
smallpox infection during a postevent vaccination program following an intentional or accidental release of the virus. No absolute
contraindications exist for
smallpox vaccination in a postevent setting. However, several relative
contraindications exist among persons with certain medical conditions. CDC recommendations for
smallpox vaccine use were developed in consideration of the risk for
smallpox infection, risk for an adverse event following vaccination, and benefit from vaccination.
Smallpox vaccines are made from live vaccinia viruses that protect against
smallpox disease. They do not contain variola virus, the causative agent of
smallpox. The three
smallpox vaccines stockpiled are
ACAM2000,
Aventis Pasteur Smallpox Vaccine (APSV), and
Imvamune. Surveillance and containment activities including vaccination with replication-competent
smallpox vaccine (i.e.,
vaccine viruses capable of replicating in mammalian cells such as
ACAM2000 and APSV) will be the primary response strategy for achieving epidemic control. Persons exposed to smallpox virus are at high risk for developing and transmitting
smallpox and should be vaccinated with a replication-competent
smallpox vaccine unless severely immunodeficient. Because of a high likelihood of a poor immune response and an increased risk for adverse events,
smallpox vaccination should be avoided in persons with severe immunodeficiency who are not expected to benefit from
vaccine, including bone marrow transplant recipients within 4 months of
transplantation, persons infected with HIV with CD4 cell counts <50 cells/mm3, and persons with
severe combined immunodeficiency, complete
DiGeorge syndrome, and other severely immunocompromised states requiring isolation. If
antivirals are not immediately available, it is reasonable to consider the use of
Imvamune in the setting of a smallpox virus exposure in persons with severe immunodeficiency. Persons without a known smallpox virus exposure might still be at high risk for developing
smallpox infection depending on the magnitude of the outbreak and the effectiveness of the public health response. Such persons will be defined by public health authorities and should be screened for relative
contraindications to
smallpox vaccination. Relative
contraindications include
atopic dermatitis (
eczema),
HIV infection (CD4 cell counts of 50-199 cells/mm3), other immunocompromised states, and
vaccine or
vaccine-component
allergies. Persons with relative
contraindications should be vaccinated with
Imvamune when available and authorized for use by the Food and Drug Administration. These recommendations will be updated as new data on
smallpox vaccines become available and further clinical guidance for other medical countermeasures including
antivirals is developed.