Summary: The swine flu vaccine program was predicated on the conclusion by Department of Health, Education, and Welfare (HEW) officials that the vaccine would protect between 70 percent and 90 percent of those vaccinated against swine flu outbreak.
This conclusion was based on a HEW review of antibody response data gathered during the 1976 swine flu vaccine trials and observations of the effectiveness of previous flu vaccines. Since scientists agree that experimental investigations involving deliberate exposure to a new virus strain, such as swine virus, are very difficult to perform and could pose a potentially serious health hazard in the United States, this method was not used to determine the effectiveness of the swine flu vaccine. The swine flu vaccine's effectiveness was estimated through clinical trials that measured the participants' antibody level before and after receiving the vaccine. HEW officials and other flu experts noted that information on possible long-term effects of flu vaccination is needed, but it would be difficult to plan and it would probably not be feasible because no one knows what to look for. As part of the swine flu immunization program, the Center for Disease Control had responsibility for conducting short-term surveillance on vaccine recipients. In addition, the Center is supporting two studies on women who received the vaccine to identify unfavorable pregnancy outcomes.
