Primary prevention measures fall into two categories. The first category includes actions to protect against disease and disability, such as getting immunizations, ensuring the supply of safe drinking water, applying dental sealants to prevent tooth decay, and guarding against accidents. Examples of primary prevention of accidents include government and state requirements for workplace safety to prevent industrial injuries and equipping automobiles with air bags and anti-lock brakes.

General action to promote health is the other category of primary prevention measures. Health promotion includes the basic activities of a healthy lifestyle: good nutrition and hygiene, adequate exercise and rest, and avoidance of environmental and health risks. Limiting exposure to sunlight, using sunscreen, and wearing protective clothing are examples of primary prevention measures to reduce the risk of developing skin cancer.

Health promotion also includes education about the other interdependent dimensions of health known as wellness. Examples of health education programs aimed at wellness include stress management, parenting classes, preparation for retirement from the workforce, and cooking classes.

Historically, public health programs in developed countries have emphasized the primary prevention of infectious diseases (illnesses caused by microorganisms) by making environmental changes, such as improving the safety and purity of food and water supplies, and providing immunizations. Figure 2.1 shows the recommended schedule of childhood immunizations—a key primary prevention measure in the United States and other developed countries.

Today, the most pressing health problems in developed countries are chronic diseases such as heart disease, cancer, and diabetes. Primary prevention of chronic diseases is more challenging than primary prevention of infectious diseases because it requires changing health behaviors. Efforts to change deeply-rooted and often culturally-influenced patterns of behaviors, such as diet, alcohol and tobacco use, and physical inactivity, generally have been less successful than environmental health and immunization programs.

Primary prevention programs are developed in response to actual and potential threats to community public health. Recent primary prevention programs have examined ways to prevent youth violence and acts of bioterrorism (use of biological or chemical weapons).

Violence on high school campuses across the United States has focused media attention on the problem of violence during childhood, adolescence, and young adulthood. In the 2003 Youth Risk Behavior Survey conducted by the CDC, more than 6 percent of students interviewed said they had carried a firearm at least once during the past month and 17.1 percent had carried a weapon such as a gun, knife, or club.

According to the CDC's National Center for Injury Prevention and Control (NCIPC), 81 percent of homicide victims ages fifteen to twenty-four were killed with firearms in 1999. In fact, firearm-related homicides were the second leading cause of injury death among teens aged fifteen to nineteen years and the third leading cause of injury death among teens aged ten to fourteen. Homicide is the second leading cause of death among young people ages fifteen to twenty-four. It is the leading cause of death for African-American (black) teenagers, the second leading cause of death for Hispanic teens, and the third leading cause of death for Native American teens.

According to the NCIPC, preliminary results from a CDC study in progress indicate that between July 1, 1994, and June 30, 1999, 253 violent deaths took place on school property, on the way to or from school, or at or on the way to or from a school-sponsored event. Most of these incidents involved firearms, and the deaths occurred in communities of all sizes, locations, income levels, and racial and ethnic makeup.

Preliminary results of the study also show that, although the number of school-associated violent death events has decreased steadily since the 1992–1993 school year, the occurrence of multiple-victim events (those with two or more deaths per event) seems to have increased. During the four school years from August 1995 through June 1999, there were fifteen multiple-victim events, compared to three multiple-victim events occurring between August 1992 and July 1995.

To develop programs to prevent violence and violent deaths among children and teens, the CDC followed a systematic public health approach to identify and describe the problem, design and evaluate measures to prevent the problem, and put those measures in place in the community. The approach that public health professionals use to develop all prevention programs consists of the following steps, some of which may be conducted simultaneously:

• Surveillance—The first step is to collect and analyze data to determine the size and scope of the problem. To understand youth violence, researchers looked at how many people were injured or killed as a result of youth violence. They looked at the ages, attitudes, school performance, family histories, and other characteristics of the children and teens who committed violent acts. They also noted when (day, night, weekends, summer, winter, spring, or fall) and where (school, home, public parks) violence occurred.
• Determining the Cause—By analyzing the data collected in the surveillance process, researchers can identify the underlying causes of the problem. Once public health professionals know who is at risk for a particular problem and why a certain group is at risk, they are better able to design actions to prevent it. Table 2.1, a list of potential participants for anti–youth violence interventions, notes risk factors and high-risk behaviors likely to lead to violence among children and adolescents.
• Develop and Test Preventive Measures—Using the results of the data analysis, public health professionals develop prevention programs called interventions. These interventions target specific populations and may be conducted at specific locations. (See Table 2.1 and Table 2.2.) Before recommending widespread use of interventions, health professionals test the programs to find out if they work as effectively as hoped. Every intervention is evaluated to find out if it achieves its objectives. Table 2.3 is an example of the goal—reducing expulsions from fights in middle schools—of an intervention and its measurable objectives.
• Implementation—During this phase, the preventive measures found to be effective are communicated so they may be put into action. To communicate methods to prevent violence among children and teens, the CDC conducted training programs, published articles in journals for public health workers and health care practitioners, and produced a book of recommended programs entitled Best Practices of Youth Violence Prevention: A Sourcebook for Community Action.

TABLE 2.1
Potential participant groups for interventions to prevent youth violence