Aerosols Transmission and Superspreaders

Question 1

What are the five major modes of microbial transmission?

Answer 1

1) Airborne
2) Faeco-oral
3) Parenteral
4) Sexual
5) Direct contact skin-to-skin

Question 2

How do airborne and droplet transmission differ?

Answer 2

1) Droplets are larger and fall quickly
2) Aerosols are smaller, remain suspended and can travel further

Question 3

What does droplet fall velocity depend in?

Answer 3

Droplet diameter - larger droplets fall faster than smaller ones

Question 4

What are the components of the chain of infection?

Answer 4

1) Reservoir
2) Source
3) Mode of transmission
4) Susceptible host

Question 5

How can infection be controlled effectively?

Answer 5

Breaking any link in chain of infection (e.g., isolation, masks/hygiene

Question 6

When does viral load peak for influenza and SARS?

Answer 6

1) Influenza - 2 days post exposure
2) SARS - 6-11 days after symptom onset

Question 7

Why was SARS easier to control than influenza/COVID-19?

Answer 7

Peak infectivity came after symptoms began - allows time for isolation

Question 8

What is the formula for the basic reproductive number (R₀)?

Answer 8

R₀ = β × X × D (transmission rate × susceptible population × duration of infectiousness)

Question 9

What does a high R₀ imply?

Answer 9

A more explosive outbreak but also a potential for rapid exhaustion of susceptibility

Question 10

What is a superspreader?

Answer 10

Individual who infects disproportionately large no. of people

Question 11

What is the 20/80 rule?

Answer 11

20% cases cause 80% of transmission

Question 12

What did Denmark COVID-19 study reveal about superspreading?

Answer 12

10% of infected individuals were responsible for 85% of all secondary cases

Question 13

Do superspreaders have more severe illness?

Answer 13

Many superspreaders have mild/no symptoms

Question 14

What factors influence whether someone becomes a superspreader?

Answer 14

1) Biological factors (e.g., viral load)
2) Social factors (e.g., no. of contacts)

Question 15

Why is identifying superspreaders important in outbreak control?

Answer 15

Targeting them can dramatically reduce transmission - more than average-based strategies

Question 16

Why might spraying public bins not be effective against COVID-19?

Answer 16

Surface (fomite) transmission plays minor role compared to airborne spread

Question 17

What are key non-pharmaceutical interventions for airborne diseases?

Answer 17

1) Masking
2) Ventilation
3) Isolation
4) Quarantine
5) Early detection