Virus Quiz : Test your knowledge

1. Which of the following most appropriately defines a “vector competence” in viral transmission?

1. Ability of a vector species to bite humans frequently.
2. Intrinsic capacity of a vector to acquire, maintain, and transmit a specific virus.
3. Ability of a vector to survive in urban environments.
4. Number of eggs laid by the vector per day.

2. With reference to “pre-symptomatic transmission” of a respiratory virus, which of the following is/are correct?

1. Transmission occurs before the infected individual develops noticeable symptoms.
2. It complicates containment strategies based solely on symptom screening.
3. It implies that symptomatic individuals never transmit the virus.

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

3. “Basic reproduction number” (R₀) of a virus is defined as the:

1. Average number of secondary infections caused by a typical infectious case in a fully susceptible population.
2. Total number of cases in the entire epidemic.
3. Maximum possible number of mutations per replication.
4. Ratio of deaths to total infections.

4. In many arboviral diseases, “bridge vectors” are important because they:

1. Transmit virus only between wildlife species and never to humans.
2. Link transmission between animal reservoirs and humans.
3. Eliminate the need for any reservoir host.
4. Prevent viral replication inside their bodies.

5. With reference to “serial cross-sectional surveys” for a viral infection in a population, their primary use is to:

1. Follow the same individuals over time for disease progression.
2. Estimate how prevalence or seroprevalence changes over time using different samples at each round.
3. Measure only mortality rates.
4. Detect only new variants in the laboratory.

6. In a viral disease outbreak, a “cluster” is best described as:

1. A single case detected in isolation.
2. Aggregation of cases in time and/or place that is suspected to be greater than expected.
3. Only laboratory-confirmed deaths.
4. All cases occurring nationwide over several years.

7. Which one of the following best describes “attack rate” in an outbreak confined to a school hostel?

1. Number of deaths divided by total hostel residents.
2. Number of new cases during the outbreak divided by total hostel residents at risk.
3. Number of recovered cases divided by total cases.
4. Number of days between first and last case.

8. “Case–control study” design is particularly useful in viral outbreak investigations to:

1. Estimate prevalence of infection in the population.
2. Identify exposures or risk factors associated with becoming a case.
3. Directly measure incidence rates over time.
4. Test vaccine efficacy in randomized fashion.

9. In the context of a novel viral vaccine, “correlate of protection” refers to:

1. A specific immune marker that is statistically associated with protection from disease.
2. Any laboratory test performed on blood.
3. Number of doses recommended in the schedule.
4. Duration of the clinical trial.

10. In a viral epidemic where R_t has been brought just below 1 through interventions, which of the following is the MOST likely consequence if all interventions are abruptly removed?

1. R_t will remain below 1 permanently.
2. R_t is likely to rise above 1 again, risking resurgence.
3. The virus will instantly disappear from the population.
4. Case numbers will remain fixed at the current level indefinitely.