CDC's Mission

The mission of the Centers for Disease Control and Prevention (CDC) is to be the national leader in disease prevention and control in the United States. It serves this mission partly through public health-related research, facilitated by a unique integration among epidemiology, statistics, and laboratory science. That research provides the basis for CDC's voluntary guidelines and recommendations. CDC also provides consultation and assistance to federal agencies, state and local health departments, other nations, and international agencies. This consultation and assistance function has been notable in the blood arena, where CDC has provided data and expert opinion to the Food and Drug Administration (FDA).

Effectiveness of CDC

The influence that CDC has in national health policy can be attributed to several factors. First, CDC is not a regulatory agency and has no regulatory authority, even though it does have a public health mandate. Thus, the only way that CDC can exert influence is to build consensus. Accordingly, the emphasis is on data-based decision-making and an intense effort at consensus building as the basis for its recommendations. Second, CDC enjoys a strongly positive public perception. Third, it has developed the ability to disseminate data and recommendations rapidly through scientific publications and, more importantly, through the Morbidity and Mortality Weekly Report (MMWR).

Research on HIV

Although many of CDC research efforts concentrate on the human immunodeficiency virus (HIV), they are applicable to other transfusion-transmissible diseases as well. In one such interview-based study funded by CDC, HIV-seropositive donors at 20 blood centers are interviewed for HIV risk factors, their motivations for donation, and other behavioral characteristics. CDC has also funded a national database with information from 19 American Red Cross blood centers, including all infectious disease marker, demographic, and donation history data. These investigations have proven vital for studying the risk of HIV transmission by transfusion. Another study of seroconverting blood donors has helped to define the "window period of infectivity. These activities occur in conjunction with ongoing investigations of disease outbreaks, including individual transfusion-associated instances of hepatitis as well as HIV.

Internationally, through a cooperative agreement with the U.S. Agency for International Development, CDC investigates the degree and quality of blood screening in other countries and assesses the feasibility of recruiting low-risk donors and developing methods for rapidly evaluating blood safety and transfusion practices.

How CDC Affects Policy

In addition to its formal recommendations and published policies, CDC influences policy regarding blood safety in a number of ways. One is the collection and publication of scientific data from studies such as those just described. Such data can have a significant impact, particularly when they are presented to venues such as the Blood Products Advisory Committee or when they become part of the CDC's congressional testimony or expert opinion to congressional staff. For example, largely on the basis of surveillance data on HIV type 2 (HIV-2) presented at the Blood Products Advisory Committee, FDA decided to defer HIV-2 screening until the HIV-1/HIV-2 combination screening enzyme immunoassay was licensed.

CDC also supports research in public health intervention, much of which directly affects transfusion medicine. For example, HIV counseling and testing sites were funded by CDC in 1985, partially to dissuade HIV-positive people from going to blood centers to be tested.

Formal Recommendations

There is no set formula for issuing formal recommendations, although there are some common steps. The first is to identify the problem. CDC has a national mandate to conduct infectious disease surveillance. State and local health departments and other agencies report unusual disease occurrences, particularly those that involve multiple states. Thus, CDC can rapidly identify large or unusual public health problems and, if appropriate, conduct an epidemiological study. One recent blood-related example was the matter of idiopathic CD4+ T-lymphocytopenia (ICL). Once the potential problem was identified, CDC acted as a convener of transfusion experts and other relevant scientists to discuss it and implemented a surveillance system.

Occasionally, CDC will create interagency task forces within the public health service, such as the AIDS Executive Task Force which coordinated many of the early AIDS activities. These groups can then act as the sites for policy formulation.

Once the relevant information is gathered, recommendations are issued in draft form. CDC then tries to achieve consensus on the draft recommendations by, for example, hosting a meeting of experts and other relevant parties. A draft copy of the consensus is often sent to various constituency groups, and the draft recommendations are published in the Federal Register, particularly if the issue is one with a high profile. Public meetings may be held to discuss the issue further. A final recommendation may then be made and may be published in MMWR or in a scientific article. (The advantage of MMWR is that CDC can disseminate the recommendation and background information within 2 days.) The recommendations concerning donor screening made and published in MMWR prior to 1985 were formal recommendations by the U.S. Public Health Service, although notice was given that there was not a full consensus about them.

Other recommendations have addressed HIV antibody testing of blood and plasma, including topics such as interpretive criteria for Western blots, recommendations for screening, and what to tell and what not to tell a person who has been tested. Other recommendations concerning phlebotomy and laboratory procedures have been issued, such as universal precautions.