Virus Quiz : Test your knowledge

1. The “infectious period” of a viral disease most appropriately refers to the time interval during which:

1. The virus can be detected in any laboratory test.
2. An infected person can transmit the virus to susceptible individuals.
3. Clinical symptoms are at their maximum severity.
4. The host immune response is completely absent.

2. Which of the following features of a virus would most strongly favour airborne (aerosol) transmission?

1. Ability to remain viable in small aerosol particles over time.
2. Exclusive replication in the gastrointestinal tract.
3. Requirement for direct blood-to-blood contact.
4. Strict dependence on an arthropod vector for spread.

3. With reference to “immune-mediated pathology” in viral infections, which of the following is/are correct?

1. Host immune responses can sometimes cause tissue damage independent of direct viral cytopathic effect.
2. Cytokine dysregulation can contribute to severe disease manifestations.
3. It implies that the virus itself never damages host cells.

Select the correct answer using the code below:

1. 1 and 2 only
2. 1 and 3 only
3. 2 and 3 only
4. 1, 2 and 3

4. In the context of vaccine-preventable viral diseases, “primary vaccine failure” refers to:

1. Gradual waning of initially adequate immunity over time.
2. Failure to mount an adequate immune response soon after vaccination.
3. Mutation of the virus after vaccination.
4. Inability to store vaccines at low temperatures.

5. “Viral shedding in the absence of symptoms” has which of the following implications for control strategies?

1. Symptom-based screening alone may miss infectious individuals.
2. Testing strategies may need to include asymptomatic high-risk contacts.
3. Transmission cannot occur until symptoms are present.

Select the correct answer using the code below:

1. 1 and 2 only
2. 1 and 3 only
3. 2 and 3 only
4. 1, 2 and 3

6. Which of the following best explains why “closed populations” (e.g., cruise ships, hostels) are often used to study viral transmission parameters?

1. They eliminate biological variability between individuals.
2. They provide relatively well-defined populations with known denominators and contact patterns.
3. Viruses behave differently only in such settings.
4. Ethical principles do not apply in closed populations.

7. In modelling viral epidemics, “superspreading” is often represented by:

1. Assuming that every infected individual infects exactly R₀ others.
2. Using overdispersed transmission models where a small fraction of cases cause many secondary infections.
3. Assuming uniform mixing with equal transmission probability for all individuals.
4. Excluding heterogeneity from the model.

8. Which one of the following best describes “cross-protection” between related viral strains?

1. Protection against a virus by prior infection or vaccination with an unrelated bacterium.
2. Partial or complete protection against one viral strain induced by immune responses to another related strain.
3. Protection that occurs only when two viruses infect simultaneously.
4. Protection that requires complete genetic identity between strains.

9. In designing non-pharmaceutical interventions (NPIs) for a respiratory virus, which pair of parameters from the SIR framework is most directly targeted?

1. Contact rate and probability of transmission per contact.
2. Recovery rate and birth rate.
3. Natural death rate and mutation rate.
4. Incubation period and vaccine efficacy.

10. For a vector-borne viral disease, which of the following interventions acts most directly on the “vectorial capacity”?

1. Mass vaccination of humans without any change in vector population.
2. Reducing mosquito lifespan and density through larval source management and insecticides.
3. Improving chlorination of drinking water.
4. Mandating the use of face masks in all public spaces.