1. Establishing Vaccination Policies
Day 2: Community Immunity

2. Warmup Get out your green “Key Questions” worksheet
Update the “Relevant Facts” section with the following key points:
Chances of contracting disease, and harm from disease VARIES
Vaccine risks are low (a few exceptions)
Childhood infectious disease has been nearly eliminated due to vaccinations
Sometimes outbreaks occur due to vaccine failure or because people have not been vaccinated
Every state allows at least one type of exemption to mandatory vaccination policy (medical, religious, philosophical)

3. Reminder… Test Friday Study: Chapter 19: Virus and Bacteria
Chapter 40: Immune System
Study:
Learning Targets
Reading Guides
Immune response worksheet (blue)
Blood Type chart

4. Community Immunity
The simulation demonstrates why people might choose not to be vaccinated and addresses the possible implications of their actions for the greater community

5. Community Immunity Simulation Overview
Shows the spread of a hypothetical disease in a population. There are two rounds:
Round One: everyone is susceptible to the disease
Round Two: a majority of the people in the community are immune, but some are susceptible for various reasons
After each day, you will hold a red (sick) or yellow (healthy)card and record results in your data sheet

6. Ground Rules for CI Simulation
You are infectious for one “day” only
When you are infectious, you infect two other students
The index (first) case will tag two individuals sitting nearby, who will then become sick
Anyone who is infected gets sick and remains sick
In each day that follows, anyone who is newly sick (has just been tagged) tags two additional people
Vaccinated people cannot tag anyone

7. Red = sick
Yellow = healthy
Round 1: Everyone is susceptible

8. Round 1 Summary
When everyone is susceptible (no one is immune)… a disease spreads quickly through a population

9. Round 2 Some individuals are immune
Read your Vaccination Status Card and keep it secret
About 65% of students are vaccinated
If you are TAGGED and you are…
…SUSCEPTIBLE, you become INFECTED
…IMMUNE, you do not become infected
…SUSCEPTIBLE and DIE, you become INFECTED, but you CANNOT TAG anyone else

10. Round 2 Summary
How was the spread of the disease different in round 2 than in round 1?
When enough people are immune to prevent the spread of the disease throughout the population… many susceptible people will be protected
Who was susceptible but did not get the disease?

11. Let’s Discuss… What is community immunity?
When a critical percentage of a population is immune to a particular infectious disease (through vaccination), the disease can no longer circulate in the community
Chances that a non-vaccinated person gets a disease are greatly diminished. There are far fewer people from whom an unvaccinated person can contract the virus
However, the risk is not entirely eliminated.
Parents who opt out of vaccinations reduce overall community immunity and place their own children at risk

12. Let’s Discuss… Is it fair?
Benefits and risks of the vaccine: are they shared equally among the vaccinated and unvaccinated?

13. Let’s Discuss…
What would happen in the number of vaccinated people increased? Decreased?
What does this simulation reveal about protecting the most vulnerable members of the population: babies too young for vaccinations, people who don’t have good access to health care, etc.
Are vaccination programs designed to protect the individual, community, or both?

14. Let’s Discuss…
How might characteristics of the disease and vaccine affect community immunity?
The percentage of vaccinated people in the community for community immunity varies
Mumps: 75-86%
Pertussis: 94%
Smallpox: 85%
Polio: 80-86%

15. Relevant Facts
Add a sentence about community immunity to your “Relevant Facts” section
Community immunity occurs when a large percentage of the population is vaccinated.
It can prevent disease from becoming widespread and protects those who cannot be or choose not to be vaccinated.

16. Who are the stakeholders?
When considering the question: “Under what circumstances should a state grant exemptions to its school vaccination policy?”, who has an interest in this issue?
School
Parents
Students
Teachers
Medical community
Larger community
School board
State public health department
Others?

17. Community Immunity Reflection
Answer questions #1-3

18. Online Community Immunity Simulator
National Institutes of Health Office of Science Education Website