The impact vaccines have had on public health cannot be overstated, saving millions of lives every year and preventing disease in millions more. That being said, vaccines are not 100% safe. Some question the importance of mandated vaccination programs for rare diseases, as well as for diseases with high survival rates. Persistent conspiracy theories and gripping anecdotes have spawned anti-vaccination movements in pockets around the world. How can a chiropractor best serve their patient community in the midst of wide-ranging information, not to mention personal and professional philosophical beliefs? Part I of this course will review basic information on infectious diseases and immunity, and explore how vaccines have revolutionized public health. It will also take a close look at vaccine development and manufacturing, in context of mandated vaccination programs. Part two of this course will explore contemporary controversies about vaccinations, and how the chiropractic community can responsibly engage in the discussion.