Question 1

Which of the following best explains why the introduction of the polio and measles vaccines led to a dramatic decrease in the number of reported cases, as shown in the graphs?

Accepted Answer

Vaccines stimulate the immune system to develop memory cells, leading to long-term immunity in the population.

Question 2

A patient is exposed to tetanus toxin and receives an injection of antitoxin antibodies. Which type of immunity is this, and why is it considered short-term?

Accepted Answer

Passive immunity; because the injected antibodies degrade over time and do not generate memory cells.

Question 3

Why are some vaccines, such as the MMR vaccine, administered in two doses?

Accepted Answer

The first dose produces mostly IgM, and the second dose induces a stronger, longer-lasting IgG response.

Question 4

Which of the following best describes herd immunity?

Accepted Answer

The resistance of a group to infection due to a high proportion of immune individuals, limiting disease transmission.

Question 5

A new vaccine is developed using a genetically engineered protein from a virus. Which class of vaccine does this represent?

Accepted Answer

Recombinant vaccine

Question 6

Which of the following is a key reason why attenuated (live) vaccines often generate a more robust immune response than subunit vaccines?

Accepted Answer

Attenuated vaccines contain whole cells that can replicate, producing many antigens and stimulating a strong immune response.

Question 7

In the SIR model of disease spread, what does the 'R' compartment represent, and why is it important for public health?

Accepted Answer

'R' stands for 'Recovered,' representing individuals who are immune and no longer contribute to disease transmission.

Question 8

A person bitten by a venomous snake receives antivenin. What is the primary role of the antibodies in this treatment?

Accepted Answer

Neutralization of the venom to prevent its activity in the body

Question 9

Which of the following diseases requires the highest percentage of herd immunity to prevent outbreaks, according to the provided table?

Accepted Answer

Measles

Question 10

Why is disease surveillance critical for epidemiologists in controlling infectious diseases?

Accepted Answer

It allows for the identification of disease origin and mode of transmission by tracking cases.

Question 11

Which of the following best describes the difference between isolation and quarantine?

Accepted Answer

Isolation separates infected individuals, while quarantine separates exposed individuals during the incubation period.

Question 12

Which antibody class is most prevalent after the first dose of a vaccine, and which is most prevalent after the second dose?

Accepted Answer

IgM after the first dose, IgG after the second dose

Question 13

Which of the following is NOT a method used to control the spread of infectious diseases in populations?

Accepted Answer

Allowing natural infection to spread unchecked

Question 14

A toxoid vaccine is best described as:

Accepted Answer

A vaccine containing inactivated toxins that stimulate an immune response without causing disease

Question 15

Which of the following is a real-world example of pathogen eradication?

Accepted Answer

The global elimination of smallpox through vaccination and surveillance

Question 16

If a disease has a basic reproduction number $$R_0 = 18$, what percentage of the population must be immune to achieve herd immunity? (Use the formula H = 1$$ - \frac{1}{$$R_0$$}$$)

Accepted Answer

$$H = 1 - \frac{1}{18} = 0.94 or 94$$%

Question 17

Which of the following best explains why combination vaccines are used in immunization schedules?

Accepted Answer

They provide immunity to multiple pathogens with fewer injections.

Question 18

Which of the following is a reportable disease in the United States, according to the CDC?

Accepted Answer

Cholera

Question 19

A patient receives a subunit vaccine. Which of the following is true about this type of vaccine?

Accepted Answer

It contains only immunogenic fragments of the microbe, not the whole organism.

Question 20

Which of the following best describes the role of mathematical models such as the SIR model in epidemiology?

Accepted Answer

They help predict and limit the spread of disease by modeling susceptible, infectious, and recovered populations.

unit 5 lecture 1

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