How do vaccines work?
Lesson 6
What is the science behind vaccines?
Learning outcomes
- Students will understand how vaccines use the bodies immune system to protect against pathogens
- Students will understand that there are different types of vaccinations
- Students will understand that not everyone can have a vaccine and that herd immunity protects vulnerable individuals
- Students will use scientific knowledge and critical thinking and perspective taking skills to evaluate different opinions about vaccination
Pathogen: A bacterium, virus, or other microorganism that can cause disease
Herd immunity: A form of immunity that occurs when a significant part of the population is vaccinated and can provide protection for individuals without sufficient immunity
Science understanding
Biological sciences
Describing how the requirements for life (for example oxygen, nutrients, water and removal of waste) are provided through the coordinated function of body systems such as the respiratory, circulatory, digestive, nervous and excretory systems
Explaining how body systems work together to maintain a functioning body using models, flow diagrams or simulations
Investigating the response of the body to changes as a result of the presence of micro-organisms
Science as a human endeavour
Scientific understanding, including models and theories, is contestable and is refined over time through a process of review by the scientific community
Advances in scientific understanding often rely on technological advances and are often linked to scientific discoveries
People use scientific knowledge to evaluate whether they accept claims, explanations or predictions, and advances in science can affect people’s lives, including generating new career opportunities
Values and needs of contemporary society can influence the focus of scientific research
Science enquiry skills
Formulate questions or hypotheses that can be investigated scientifically
Analyse patterns and trends in data, including describing relationships between variables and identifying inconsistencies
What is a vaccine?
A vaccine contains an altered (attenuated) version of a pathogen, its toxin or a protein/particle from its outer coat
The altered state of the pathogen could be weakened or dead. Sometimes only a part of the pathogen is used in a vaccine – called the antigen
There are new cutting edge vaccines that only use DNA and mRNA from the pathogen
How do vaccines work?
A vaccine causes the body to produce antibodies and memory cells that act against the target pathogen, without making the person ill
If a vaccinated person is later infected by the same pathogen, their immune system recognises it and can destroy it very quickly
Vaccines build herd immunity
Herd Immunity
Herd immunity (also called herd effect, community immunity, population immunity, or social immunity) is a form of indirect protection from infectious disease that occurs when a large percentage of a population has become immune to an infection, whether through vaccination or previous infections, thereby providing a measure of protection for individuals who are not immune
In a population in which a large proportion of individuals possess immunity, such people being unlikely to contribute to disease transmission, chains of infection are more likely to be disrupted, which either stops or slows the spread of disease
The greater the proportion of immune individuals in a community, the smaller the probability that non-immune individuals will come into contact with an infectious individual, helping to shield non-immune individuals from infection
Meet Prof Robert Booy: 10 and 20 years ago, discussing herd immunity
Prof Booy has researched the benefits of vaccination for 35 years
Class activity
Scenario 1 – No vaccination
All the students stand up in the room. They must be within arms reach of each other
Choose one person to have a disease, such as tuberculosis, which is spread through coughing
They are given a card of red dot stickers which represent TB. (They should also have a red dot sticker on to show that they have the disease)
When they “cough” they pass the card on to the person standing next to them – they have now caught TB and will keep a red dot sticker
This person then “coughs” and passes the card along
Eventually the whole class will have been passed the card have a red dot sticker on and have therefore “have” TB
Scenario 2 – 50% vaccinated
Set the scene as for scenario 1 but this time randomly give 50% of the class green stickers – this means half the children will not be protected
Now, have the sick person “cough” again but now they can’t pass the red stickers to anyone with a green sticker – they are protected from the immunisation
Half of the class will be protected. See how far the red sticker can get
It will likely still make some children sick, but not all. This not a full herd immunity but a partial immunity
Scenario 3 – 90% vaccinated
Set the scene as for scenario 1 but this time randomly give 90% of the class green stickers – this means only 2 or 3 children will not be protected
Now, have the sick person “cough” again but now they can’t pass the red stickers to anyone with a green sticker – they are protected from the immunisation
Most of the class will be protected
Because the red sticker can’t be passed further than one person at a time, the “unvaccinated” students should be safe
This is called herd immunity and is vital to protect vulnerable members of our society
World Health Organisation – How Do Vaccines Work?
The Children’s Hospital of Philadelphia – Vaccine Science: Evaluating Scientific Information and Studies
High School | The Vaccine Makers Project
Coming soon
Coming soon
Summary
A vaccine protects against an infectious disease. It contains an altered (attenuated) germ or an outer bit of the germ which stimulates the body to build antibodies to protect against the infection
Herd immunity is built when enough people have had a vaccine and have had the infection and survived
Quiz
1) Vaccines
a) Are chemicals that teaches the body’s immune system how to fight diseases
b) Is a really cool English indie rock band
c) Are altered versions of pathogens or their toxins that teaches the body’s immune system how to fight diseases
d) Are altered versions of pathogens or their toxins that cause infections
2) _______ is when a large enough percentage of the population is immune to a disease to stop it spreading, thereby protecting those who are not immune
a) Community immunity
b) Herd immunity
c) Population immunity
d) All of the above
3) A vaccine works by
a) Killing the pathogen in the body
b) Teaching the body to produce antibodies and memory cells to act against the pathogen without making the person ill
c) Producing antibodies and memory cells to act against the pathogen without making the person ill
d) Changes the pathogen’s DNA so it doesn’t work anymore
4) A bacterium, virus or other microorganism that can cause disease is a
a) Pathogen
b) Parasite
c) Illness
d) Symbiote