Virus Quiz : Test your knowledge

1. “Incubation period” vs “latent period” in viral infections: which statement is correct?

1. Both necessarily end on the same day.
2. Incubation period ends at symptom onset, while latent period ends when the person first becomes infectious.
3. Latent period refers only to viruses that integrate into the host genome.
4. Incubation period refers only to chronic infections.

2. In the epidemiologic triad (agent–host–environment) for viral diseases, which of the following is primarily an “environment” factor?

1. Age distribution of the population.
2. Population density and crowding in urban housing.
3. Viral mutation rate.
4. Host genetic susceptibility loci.

3. With reference to “waning immunity” after viral infection or vaccination, which of the following is/are correct?

1. Antibody titres and protection can decline over time.
2. Booster doses may be needed to restore protective immunity.
3. Waning immunity means immune memory is completely lost instantly.

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. “Viral shedding dynamics” influence control measures because:

1. They determine when and where the virus is released from the body.
2. They help identify periods of highest infectiousness.
3. They guarantee that shedding stops when symptoms begin.
4. They only apply to vector-borne viruses.

5. For an emerging respiratory virus, which of the following combinations BEST captures “layered” public health interventions?

1. Vaccination alone at any coverage.
2. Masking, ventilation, physical distancing, vaccination, and testing combined.
3. Border closures without local measures.
4. Only treating severe cases with antivirals.

6. In sero-surveys for a viral infection, which statement is generally correct?

1. They measure current viral load directly.
2. They provide estimates of proportion of the population with evidence of past infection or vaccination.
3. They can never miss mild or asymptomatic infections.
4. They are useful only after the epidemic has completely ended.

7. In many viral infections, “age-specific attack rates” are important because they:

1. Reveal which age groups are disproportionately affected.
2. Help prioritize vaccine allocation and school/college policies.
3. Are always identical across all age groups.

Select the correct answer using the code below:

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

8. “Asymptomatic seropositive” individuals for a virus MOST likely indicate that:

1. Infection occurred in the past without noticeable illness.
2. Laboratory test is definitely wrong.
3. They cannot transmit the virus under any circumstance.
4. They will necessarily develop severe disease later.

9. In the context of vaccines for rapidly mutating RNA viruses, “strain update” is needed primarily because:

1. Old vaccines expire in cold storage regardless of virus evolution.
2. Antigenic changes may reduce match between circulating strains and vaccine strains.
3. Manufacturers must change composition every year by regulation.
4. Virus becomes completely non-pathogenic over time.

10. For a faeco-oral viral disease, which combined strategy BEST addresses the “environment” and “host” components simultaneously?

1. Improved water/sanitation only.
2. Vaccination only.
3. Safe water, sanitation and hygiene (WASH) improvements plus vaccination of susceptible groups.
4. Vector control with insecticides only.