APHA Vaccine-Preventable Diseases & Immunology 2 — Questions and Answers
Question 1: Which type of immunity is conferred when a vaccinated individual protects unvaccinated members of a community by reducing pathogen circulation?
- Passive immunity
- Herd immunity (Correct answer)
- Cell-mediated immunity
- Innate immunity
Correct answer: Herd immunity
Herd immunity (community immunity) occurs when a sufficient proportion of a population is immune, reducing transmission and protecting those who cannot be vaccinated.
Question 2: A child receives antibodies through breast milk that protect against rotavirus. This is an example of which type of immunity?
- Active natural immunity
- Passive natural immunity (Correct answer)
- Active artificial immunity
- Passive artificial immunity
Correct answer: Passive natural immunity
Passive natural immunity occurs when antibodies are transferred naturally from mother to child via breast milk or placenta, without the recipient mounting their own immune response.
Question 3: Pertussis (whooping cough) is caused by which organism?
- Haemophilus influenzae type b
- Bordetella pertussis (Correct answer)
- Streptococcus pneumoniae
- Neisseria meningitidis
Correct answer: Bordetella pertussis
Bordetella pertussis is the gram-negative bacterium responsible for pertussis, characterized by severe paroxysmal coughing fits followed by an inspiratory whoop.
Question 4: Which vaccine component is responsible for stimulating an immune response without causing disease?
- Adjuvant
- Antigen (Correct answer)
- Preservative
- Stabilizer
Correct answer: Antigen
The antigen is the component of a vaccine that the immune system recognizes and responds to, generating memory cells and antibodies without causing infection.
Question 5: Mumps primarily targets which organ system, potentially causing a serious complication in post-pubertal males?
- Respiratory system causing pneumonia
- Salivary glands and potentially testes causing orchitis (Correct answer)
- Central nervous system causing encephalitis exclusively
- Cardiovascular system causing myocarditis
Correct answer: Salivary glands and potentially testes causing orchitis
Mumps classically causes parotitis (salivary gland swelling) and can cause orchitis in post-pubertal males, which may rarely lead to infertility.
Question 6: Varicella-zoster virus (VZV) can reactivate later in life to cause which condition?
- Rubeola
- Herpes zoster (shingles) (Correct answer)
- Roseola infantum
- Hand-foot-and-mouth disease
Correct answer: Herpes zoster (shingles)
After primary varicella (chickenpox) infection, VZV remains latent in dorsal root ganglia and can reactivate as herpes zoster (shingles), typically in older or immunocompromised individuals.
Question 7: What is the primary mechanism by which inactivated vaccines stimulate immunity?
- They replicate inside host cells to produce antigens over time
- They present killed or inactivated pathogens to trigger antibody production without infection (Correct answer)
- They transfer donor antibodies directly into the recipient
- They suppress T-cell activity to prevent autoimmune responses
Correct answer: They present killed or inactivated pathogens to trigger antibody production without infection
Inactivated vaccines contain killed pathogens or their components; the immune system recognizes the antigens and generates antibodies and memory cells without risk of disease from the vaccine itself.
APHA Vaccine-Preventable Diseases & Immunology 2
Which type of immunity is conferred when a vaccinated individual protects unvaccinated members of a community by reducing pathogen circulation?