Answer to Question 1
Correct Answer: 3
Rationale 1: Titers do not estimate the degree of infection.
Rationale 2: It is not possible to measure the amount of vaccine present in the bloodstream.
Rationale 3: Titers measure the amount of antibodies.
Rationale 4: The amount of antigen is not measured in titers.
Global Rationale: The effectiveness of most vaccines can be assessed by measuring the amount of antibodies produced after the vaccine has been administered, a quantity called titer. Titers do not measure degree of risk for future infection, amount of vaccine in the bloodstream, or the amount of antigen in the bloodstream.
Answer to Question 2
Correct Answer: 3
Rationale 1: Polio was not the first disease to be prevented by inoculation.
Rationale 2: Anthrax was not the first disease to be prevented by inoculation.
Rationale 3: The first major disease to be prevented by inoculation was smallpox.
Rationale 4: Measles was not the first disease to be prevented by inoculation.
Global Rationale: In the 1790s, Dr. Edward Jenner was experimenting with the use of inoculation, the placement of a foreign substance on or in an individual for the purpose of disease prevention. Inoculation uses live virus particles obtained from an infected patient. Jenner used the cowpox virus, a benign pathogen in humans, because he predicted that exposure to that virus would provide immunity to smallpox, which was one of the most dreaded human diseases of that era. Jenner's inoculation of a single 8-year-old boy ultimately led to one of the greatest triumphs in disease prevention. Vaccines for polio, anthrax, and measles were developed later.