This report supplements the 2001 statement by the Advisory Committee on Immunization Practices (ACIP) (CDC. Vaccinia [smallpox] vaccine: recommendations of the Advisory Committee on Immunization Practices [ACIP], 2001. MMWR 2001;50[No. RR-10]:1-25). This supplemental report provides recommendations for using smallpox vaccine in the pre-event vaccination program in the United States. To facilitate preparedness and response, smallpox vaccination is recommended for persons designated by public health authorities to conduct investigation and follow-up of initial smallpox cases that might necessitate direct patient contact. ACIP recommends that each state and territory establish and maintain > or = 1 smallpox response team. ACIP and the Healthcare Infection Control Practices Advisory Committee (HICPAC) recommend that each acute-care hospital identify health-care workers who can be vaccinated and trained to provide direct medical care for the first smallpox patients requiring hospital admission and to evaluate and manage patients who are suspected as having smallpox. When feasible, the first-stage vaccination program should include previously vaccinated health-care personnel to decrease the potential for adverse events. Additionally persons administering smallpox vaccine in this pre-event vaccination program should be vaccinated. Smallpox vaccine is administered by using the multiple-puncture technique with a bifurcated needle, packaged with the vaccine and diluent. According to the product labeling, 2-3 punctures are recommended for primary vaccination and 15 punctures for revaccination. A trace of blood should appear at the vaccination site after 15-20 seconds; if no trace of blood is visible, an additional 3 insertions should be made by using the same bifurcated needle without reinserting the needle into the vaccine vial. If no evidence of vaccine take is apparent after 7 days, the person can be vaccinated again. Optimal infection-control practices and appropriate site care should prevent transmission of vaccinia virus from vaccinated health-care workers to patients. Health-care personnel providing direct patient care should keep their vaccination sites covered with gauze in combination with a semipermeable membrane dressing to absorb exudates and to provide a barrier for containment of vaccinia virus to minimize the risk of transmission; the dressing should also be covered by a layer of clothing. Dressings used to cover the site should be changed frequently to prevent accumulation of exudates and consequent maceration. The most critical measure in preventing contact transmission is consistent hand hygiene. Hospitals should designate staff to assess dressings for all vaccinated health-care workers. When feasible, staff responsible for dressing changes for smallpox health-care teams should be vaccinated, all persons handling dressings should observe contact precautions. Administrative leave is not required routinely for newly vaccinated health-care personnel unless they are physically unable to work as a result of systemic signs and symptoms of illness; have extensive skin lesions that cannot be adequately covered or if they are unable to adhere to the recommended infection-control precautions. Persons outside the patient-care setting can keep their vaccination sites covered with a porous dressing hand hygiene remains key to preventing inadvertent inoculation. FDA has recommended that recipients of smallpox vaccine be deferred from donating blood for 21 days or until the scab has separated. Contacts of vaccinees, who have inadvertently contracted vaccinia, also should be deferred from donating blood for 14 days after complete resolution of their complication. In the pre-event vaccination program, smallpox vaccination is contraindicated for persons with a history or presence of eczema or atopic dermatitis; who have other acute, chronic, or exfoliative skin conditions; who have conditions associated with immunosuppression; are aged < 1 year; who have a serious allergy to any component of the vaccine; or who are pregnant or breastfeeding. ACIP does not recommend smallpox vaccination for children and adolescents aged < 18 years during the pre-event vaccination program. Pre-event vaccination also is contraindicated among persons with household contacts who have a history or presence of eczema or atopic dermatitis; who have other acute, chronic, or exfoliative skin conditions; who have conditions associated with immunosuppression; or who are pregnant. For purposes of screening for contraindications for pre-event vaccination, household contacts include persons with prolonged intimate contact (e.g., sexual contacts) with the potential vaccinee and others who might have direct contact with the vaccination site. Persons with inflammatory eye disease might be at increased risk for inadvertent inoculation as a result of touching or rubbing the eye. Therefore, deferring vaccination is prudent for persons with inflammatory eye diseases requiring steroid treatment until the condition resolves and the course of therapy is complete. Eczema vaccinate, a serious form of disseminated vaccinia infection, can occur among persons with atopic dermatitis and other dermatologic conditions. Potential vaccinees should be queried regarding the diagnosis of atopic dermatitis or eczema in themselves or any member of their household, or regarding the presence of chronic or recurrent rashes consistent with these diagnoses. Persons reporting such a rash in themselves or household members should not be vaccinated, unless a health-care provider determines that the rash is not eczema or atopic dermatitis. Before vaccination, women of childbearing age should be asked if they are pregnant or intend to become pregnant during the next 4 weeks; women who respond positively should not be vaccinated. Any woman who thinks she might be pregnant or who wants additional assurance that she is not pregnant should perform a urine pregnancy test on the day scheduled for vaccination. If a pregnant woman is inadvertently vaccinated or if she becomes pregnant within 4 weeks after smallpox vaccination, she should be counseled regarding concerns for the fetus. Vaccination during pregnancy should not ordinarily be a reason to terminate pregnancy. CDC has established a pregnancy registry to prospectively follow the outcome of such pregnancies and facilitate the investigation of any adverse pregnancy outcome among pregnant women who were inadvertently vaccinated. For enrollment in the registry, contact CDC at 404-639-8253. Smallpox vaccine should not be administered to persons with human immunodeficiency virus infection (HIV) or acquired immunodeficiency syndrome (AIDS) as part of a pre-event program because of their increased risk for progressive vaccinia. HIV testing is recommended for persons who have any history of a risk factor for HIV infection or for anyone who is concerned that he or she might have HIV infection. HIV testing should be available in a confidential or anonymous setting, in accordance with local laws and regulations, with results communicated to the potential vaccinee before the planned date of vaccination. Smallpox vaccine can be administered simultaneously with any inactivated vaccine. With the exception of varicella vaccine, smallpox vaccine can be administered simultaneously with other live-virus vaccines. To avoid confusion in ascertaining which vaccine might have caused postvaccination skin lesions or other adverse events, varicella vaccine and smallpox vaccine should be administered >4 weeks apart. Health-care workers scheduled to receive an annual purified protein derivative (PPD) skin test for tuberculosis screening should not receive the skin test until >1 month after smallpox vaccination. Persons with progressive vaccinia, eczema vaccinate, and severe generalized vaccinia or inadvertent inoculation might benefit from therapy with VIG or cidofovir, although the latter has not been approved by FDA for this indication. Suspected cases of these illnesses or other severe adverse events after smallpox vaccination should be reported immediately to state health departments. VIG and cidofovir are available from CDC under Investigational New Drug protocols. Clinically severe adverse events after smallpox vaccination should be reported to the Vaccine Adverse Event Reporting System. Reports can be made online at https://secure.vaers.org/VaersDataEntryintro.htm, or by postage-paid form, which is available by calling 800-822-7967 (toll-free). ACIP will review these recommendations periodically as new information becomes available related to smallpox disease, smallpox vaccines, the risk of smallpox attack, smallpox vaccine adverse events, and the experience gained as recent recommendations are implemented. Revised recommendations will be developed as needed.