Avaccine is made from *
a. proteins produced by the bodys immune system
b. a weakened or dead form of a pathogen
c. body cells that are immune to a disease
d. an antibiotic used to treat an infectious disease

vaccination

allergic reaction

t-cells

eradicated

autoimmune disease

Europeans had been exposed to the virus that causes smallpox for many generations, allowing them to acquire immunity to the virus. Native Americans were not exposed to smallpox or similar viruses before, so they had no immunity to the virus. In modern times, before traveling abroad, a person often receives vaccinations or other medications to avoid contracting the diseases specific to that region of the world.

Explanation: