When President-elect Donald J. Trump announced on Thursday that he would nominate Robert F. Kennedy Jr. to lead the Department of Health and Human Services, questions immediately arose about how the department would change if it were to be led by someone who has expressed skepticism toward vaccines and a resistance to public health measures.

If confirmed, Mr. Kennedy, who ended his presidential campaign in August and endorsed Mr. Trump, would run a department whose divisions manage billions of dollars and regulate the nation’s food, medications, vaccines and medical treatments.

The H.H.S. oversees 13 divisions that administer services and conduct research through various agencies and offices, including:

Centers for Disease Control and Prevention

The C.D.C. helps track food-borne illnesses, makes recommendations on vaccines and tracks outbreaks of infectious diseases such as the flu and measles. For instance, the agency recently coordinated with states to track illnesses and coordinate the response to a listeria outbreak related to Boar’s Head meat, and to an E. coli outbreak related to McDonald’s Quarter Pounders.

The agency also inspects public health labs and oversees safety protocols meant to safeguard the public from lab leaks of infectious diseases.

The C.D.C. oversees 10 centers and institutes, including the National Institute for Occupational Safety and Health. NIOSH helps guide the government on regulations meant to prevent work-related injuries and illnesses through research and recommendations. NIOSH was established alongside the Department of Labor’s Occupational Safety and Health Administration to collaborate on work safety issues.

National Institutes of Health

The N.I.H. wields billions of dollars in funding for studies on the treatment of diseases such as cancer and Alzheimer’s. The agency also supports studies at universities and basic science that can form the backbone of new treatments and technologies.

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