CDC mulls smallpox vaccination scenarios

Questions and options on a difficult decision

The smallpox working group at the recent meeting held by the Centers for Disease Control and Prevention (CDC) reviewed a series of issues and questions in a draft document on smallpox vaccination options. Highlights of the document are summarized as follows:

Background

If vaccination were provided pre-event, the rate of adverse events likely would be much lower as vaccination could be deferred for people who have contraindications. People who are immunocompromised because of cancer or its therapy, who have known HIV infection, or who are receiving immunosuppressive therapy can be identified readily and vaccination deferred.

People who are unaware that they are infected with HIV may be identified by questions regarding risk factors and serological testing. A history of eczema may be difficult to obtain because the prevalence is highest among infants and decreases rapidly during the preschool years; however, risk of severe reaction in an adult with a history of eczema only as an infant is likely lower than for other at-risk groups.

Deferring vaccination for household contacts of people at high risk and instructing vaccines regarding care of the vaccination site would decrease the risk of adverse reactions in contacts. Estimates of the rate of severe adverse reactions to smallpox vaccination are subject to substantial uncertainty.

Other, unpublished estimates have ranged from about < 40 to > 200 reactions per million vaccine doses administered. Population denominators for some high-risk conditions (e.g., eczema) are imprecise and the risk of severe reactions among people with the current range of immunocompromising conditions may differ from the risk experienced during the past.

Question 1

With no known cases of smallpox worldwide, should routine smallpox vaccination be re-introduced into the United States? That is, should there be any change in the current recommendation for not vaccinating people in the general population unless a smallpox bioterrorism event has occurred?

Option 1. There should be no changes in the current recommendation.

Option 2. Continue current recommendations for not vaccinating in the general population in the absence of a smallpox bioterrorist attack, but allow permissive or voluntary use of the vaccine for people in the general population who desire to be vaccinated despite the recommendation.

Option 3. There is no positive or negative recommendation. The committee is neutral but recommends that vaccine be available for individual choice.

Option 4. Routine vaccination is recommended, but there is a provision to opt out of taking the vaccine.

Question 2

Are there other occupational groups at the federal, state, or local level who should be vaccinated in a pre-attack setting in order to enhance preparedness?

Option 1. At the present time, there should be no vaccination of additional people at the state or local level. That is, the current recommendations as outlined in the Advisory Committee on Immunization Practices statement on the use of vaccinia vaccine published in June 2001 remain valid.

Option 2. Vaccination would be done from the smallest number of personnel to the largest number of personnel, and thought of as being done in an additive fashion. One needs to consider the likelihood of being exposed to smallpox, the importance of the occupation in dealing with smallpox, and the risk of vaccination to the individual.

Potential groups for immunization:

• pre-designated public health and medical personnel (including emergency department staff) who would be called upon to care for and treat smallpox patients in designated facilities;

• smallpox-response teams at the federal, state, and local levels who would be called upon to investigate smallpox cases, and contain outbreaks;

• selected first responders who would play a critical role in the control of an outbreak of smallpox;

• pre-designated personnel to maintain essential services;

• all health personnel;

• other first responders;

• others.

Option 3. State and local public health authorities are given a fixed amount of vaccine, and they determine who should be vaccinated within their state for preparedness and response enhancement.

(Editor’s note: The CDC options assume that there is a clear understanding of the risks; vaccines take appropriate care of their vaccine site; the product is available for use; there is sufficient vaccine immune globulin available; there is sufficient security; vaccines must be used under investigational new drug procedures until mid-2003; and there is appropriate screening for contraindications.)