A more thorough explanation:

The Public Health Service is a group of offices and units within the U.S. Department of Health and Human Services. Its main goal is to improve the physical and mental health of people living in the United States.

For example, the Public Health Service might:

• Provide vaccines to prevent the spread of diseases like the flu or measles
• Conduct research to better understand health issues like cancer or heart disease
• Offer education and resources to help people make healthy choices, like quitting smoking or eating a balanced diet

These examples show how the Public Health Service works to promote health and prevent illness. By providing vaccines, conducting research, and offering education, the Public Health Service helps people stay healthy and avoid getting sick.