A working group from the Advisory Committee on Immunization Practices (ACIP), the National Vaccine Advisory Committee, and the Healthcare Infection Control Practices Advisory Committee (HICPAC) recently formulated recommendations for the use of smallpox vaccine in a pre-event vaccination program. The recommendations supplement the ACIP's June 2001 guidelines on vaccinia vaccine, and were developed at the request of the Centers for Disease Control and Prevention (CDC) after the terrorist attacks on the United States in September 2001. The supplemental report was published in the April 4, 2003, issue of Morbidity and Mortality Weekly Report.

Guidelines for vaccination of laboratory personnel who directly handle orthopoxviruses have not changed. However, the supplemental report updates recommendations for the use of smallpox vaccine in persons who are designated to respond to or care for suspected or confirmed smallpox cases. The supplemental report also expands the primary strategy for controlling and containing smallpox if an outbreak should occur.

Surveillance and Containment

The CDC has developed an algorithm to help medical and public health personnel evaluate the likelihood of smallpox in the patient who has a febrile rash illness. Copies of the algorithm can be obtained from state health departments or at www.bt.cdc.gov/agent/smallpox/diagnosis/evalposter.asp. Poster copies of the algorithm can be ordered at https://www2.cdc.gov/nchstp_od/PIWeb/niporderform.asp.

The local or state health department should be contacted immediately if smallpox is a possible diagnosis. After the patient has been evaluated by the health department, the CDC's Rash Illness Evaluation team should be contacted (770-488-7100) if laboratory testing for smallpox is deemed necessary. An initial smallpox case must be laboratory confirmed by the CDC.

Surveillance and containment are the primary strategies for controlling an outbreak of smallpox and interrupting its transmission. During the smallpox era, the risk of contracting the disease was greatest in household members and close contacts of persons with smallpox. Containment measures include isolating patients with smallpox and vaccinating persons at risk for contracting the disease. If a bioterrorist attack occurs, expanded vaccination might be used. The ACIP notes that “state and local health departments should be able to vaccinate entire populations in a timely manner.”

Selected Groups for the Pre-Event Vaccination Program

To facilitate preparedness and response, vaccination against smallpox is recommended for persons who are designated to investigate and follow up initial cases of smallpox and in the course of this work might have direct patient contact. Vaccination also is recommended for persons who are responsible for administering smallpox vaccine in the pre-event vaccination program. The ACIP recommends that each territory or state establish at least one smallpox response team.

The ACIP and HICPAC recommend that every acute care hospital identify a specific group of health care workers for receipt of vaccine in the first stage of the pre-event smallpox vaccination program. The members of this team should be trained to provide emergency department evaluation and management of patients with suspected smallpox, and to provide medical care to the first hospitalized patients with smallpox for two or more days, until additional health care personnel have been vaccinated.

Smallpox Vaccine

Smallpox vaccine (Dryvax) for civilian use is available only through the CDC. Vaccination is by multiple rapid, vigorous, vertical punctures of a bifurcated needle that has been inserted vertically into a vaccine vial. The preferred site of administration is the skin over the deltoid muscle insertion or over the triceps muscle. Two to three punctures are recommended for primary vaccination; 15 punctures are recommended for revaccination. If a trace of blood does not appear at the vaccination site within 15 to 30 seconds, three more punctures should be performed without reinserting the needle into the vaccine vial.

After vaccination, the skin should be wiped with dry sterile gauze, which is then put into a biohazard waste container. A papule should develop two to five days after vaccination; the scab should separate from the skin within 14 to 21 days after vaccine receipt. If there is no evidence of vaccine “take” after one week, the vaccine can be administered again.

Smallpox vaccine and inactivated vaccines can be administered at the same time. The vaccine also can be administered with other live-virus vaccines, except varicella vaccine. Smallpox vaccine and varicella vaccine should be given at least four weeks apart.

Tuberculosis screening (i.e., purified protein derivative skin test) should not be performed until at least one month after smallpox vaccine is administered.

Prevention of Vaccinia Virus Transmission After Vaccination

Measures should be taken to prevent inadvertent vaccinia virus transmission from vaccinated health care workers who provide direct care to patients. Maximal viral shedding occurs four to 14 days after vaccination; the duration of viral shedding may be shorter in revaccinees.

The vaccination site should be kept covered with gauze and a semipermeable dressing, or with a product that combines an absorbent base with an overlying semipermeable layer. The site also should be covered with a layer of clothing. Dressings should be changed frequently.

Consistent hand hygiene is critical in preventing contact transmission. Hands should be washed with antibacterial soap and water or an alcohol rub (alcohol content: 60 percent or higher) before patient contact and after contact with the vaccination site or materials that have touched the vaccination site.

In nonpatient care settings, vaccination sites can be kept covered with gauze or another porous dressing. Careful handwashing remains critical.

The U.S. Food and Drug Administration (FDA) recommends that persons defer blood donation until 21 days after they receive smallpox vaccine or until the scab has separated from the vaccination site. Vaccinee contacts who inadvertently contract vaccinia virus should not give blood until 14 days after resolution of their complication (e.g., vaccinia virus skin infection). FDA guidance on blood donations is available at www.fda.gov/cber/gdlns/smpoxdefquar.htm.

Health care workers generally do not require administrative leave after they receive smallpox vaccine. Leave may be necessary if a worker has extensive skin lesions that cannot be covered adequately, is unable to observe recommended precautions for infection control, or has systemic signs and symptoms of illness.

Contraindications to Smallpox Vaccine in the Pre-Event Vaccination Program

In the pre-event program, smallpox vaccination is contraindicated for persons with any of the following:

• Previous or current atopic dermatitis or eczema

• Other acute, chronic, or exfoliative skin conditions (e.g., burns, impetigo, herpes, severe acne)

• Conditions associated with immunosuppression (e.g., leukemia, lymphoma, human immunodeficiency virus [HIV] infection, solid organ transplantation)

• Pregnancy or breastfeeding

• Age less than one year (Note that the ACIP does not recommend vaccination of persons younger than 18 years in the pre-event vaccination program.)

• Serious allergy to any component of smallpox vaccine

• Known underlying heart disease or three or more major cardiac risk factors.

Pre-event smallpox vaccination also is contraindicated for persons who have household contacts with any of the following:

• Previous or current atopic dermatitis or eczema

• Other acute, chronic, or exfoliative skin conditions

• Conditions associated with immunosuppression

• Pregnancy

Screening for Contraindications Before Smallpox Vaccination

Because of the increased risk of inoculation, it is prudent to defer smallpox vaccination in persons with inflammatory eye diseases requiring steroid therapy.

When smallpox vaccine is administered, persons with atopic dermatitis and other dermatologic conditions are at risk for eczema vaccinatum, a serious disseminated vaccinia virus infection. The ACIP recommends using two questions to screen for eczema and atopic dermatitis before smallpox vaccine is administered: Question 1—“Have you or a member of your household ever been diagnosed with eczema or atopic dermati-tis?”If the answer is “yes,”no vaccine is given. If the answer is “no,” the next question is asked.

Question 2—“Eczema or atopic dermatitis is an itchy, red, scaly rash that comes and goes but usually lasts [more than] two weeks. Have you or a member of your household ever had a rash like that?” If the answer is “yes,” smallpox vaccine is not given unless the person and his or her health care provider are positive that the rash is not atopic dermatitis or eczema. If the answer is “no,” the screening process for other contraindications is continued.

Before smallpox vaccine is administered, women of childbearing status should be asked: “Are you pregnant, or do you intend to become pregnant within the next month?” If the answer is “yes,” smallpox vaccine should not be given. For some assurance, a woman can perform a pregnancy test (first-morning-void urine) on the day vaccination is scheduled. The ACIP notes, however, that the woman should be informed that a negative test does not exclude very early pregnancy. If a woman becomes pregnant within four weeks after smallpox vaccination or is inadvertently vaccinated while pregnant, she should be counseled about concerns for the fetus (i.e., the possibility of fetal vaccinia virus infection). However, smallpox vaccination usually is not a reason to terminate a pregnancy.

The risk of severe adverse reactions from live-virus vaccines may be increased in persons with HIV infection or acquired immunodeficiency syndrome. The ACIP recommends that HIV testing be readily available to persons who are considering smallpox vaccination. Testing is recommended for persons who are unsure of their HIV status or have a history of a risk factor for HIV infection. Confidentiality should be maintained.

Adverse Events

Vaccinia immune globulin (VCIG) is a first-line therapy for certain adverse reactions to smallpox vaccine. Treatment with VCIG or cidofovir may be beneficial in persons with eczema vaccinatum, progressive vaccinia, and severe generalized vaccinia or inadvertent inoculation. The ACIP notes, however, that the FDA has not labeled cidofovir for these indications. VCIG and cidofovir are available from the CDC.

Suspected cases of smallpox vaccine–related illnesses and severe adverse events should be reported to the state health department. The Vaccine Adverse Event Reporting System (VAERS) should be informed about clinically severe events after smallpox vaccine administration. Reports to VAERS can be made online: secure.vaers.org/VaersDataEntryintro.htm.