There is a growing amount of misinformation online about vaccines and the potential harms they may cause. At the same time, some communities are experiencing increasing distrust in medical advice. Together, these factors have contributed to vaccine hesitancy among some families.
At Sage Medical, our goal is always to support the health and wellbeing of you and your family. Vaccines are one of the most effective ways to prevent serious infectious diseases and have played a major role in improving public health around the world.
This article explains how vaccines work and addresses some common questions and concerns.
- In this blog we’ll cover:
What herd immunity is and why it matters - What ingredients vaccines contain
- Common vaccine myths and misconceptions
What Is Herd Immunity?
Most of us have grown up in a time when many serious infectious diseases are far less common than they once were. This is largely due to high vaccination rates and the protection created by herd immunity.
Herd immunity can be thought of like a fire spreading through dry grass. If most people are vulnerable to infection, the virus can spread quickly from one person to another. But when enough people are protected through vaccination, it becomes much harder for the virus to move through the community. Eventually, the chain of infection is broken and the disease struggles to spread.
Herd immunity is particularly important for people who cannot be vaccinated themselves, including:
- newborn babies who are too young to receive certain vaccines
- older adults
- people with weakened immune systems
Viruses and bacteria need susceptible hosts (people who are not immune) in order to survive and spread. When vaccination levels are high, infections often reach a dead end because they cannot easily pass from person to person.
For some diseases, very high levels of immunity are required to prevent outbreaks. Measles, for example, requires around 95% of the population to be immune to stop it spreading. When vaccination rates fall below this level, outbreaks can occur, as has been seen in recent years in Victoria and New South Wales.
Real-World Examples of Vaccination Success
Diphtheria
Before a vaccine was introduced in the 1940s, diphtheria was a common childhood illness in the United Kingdom and caused an average of 3,500 deaths each year.
Today, because of vaccination programs, cases are now rare in many countries. However, the disease still exists in some parts of the world.
Measles
Before the measles vaccine became widely available, around 2.6 million people worldwide died each year from the disease.
Even today, measles can still be dangerous. In high-income regions, around 1 in 5,000 people infected may die. In the poorest regions of the world, the death rate can be as high as 1 in 100.
What Ingredients Are in Vaccines?
Vaccines contain carefully selected ingredients that help the immune system recognise and fight specific infections.
Antigens
Antigens are the active part of a vaccine. They train the immune system to recognise and respond to a specific virus or bacteria.
Antigens may include:
• weakened or inactive viruses or bacteria
• small parts of a virus or bacteria
• toxins produced by bacteria
• genetic material such as mRNA or DNA
Adjuvants
Adjuvants strengthen the body’s immune response to the vaccine so smaller amounts can be used while still producing strong immunity.
One commonly used adjuvant is aluminium salts, present in very small amounts (usually less than 0.5 mg per dose), far lower than the amount we are typically exposed to through food and water.
Stabilisers help keep vaccines effective during storage and transport. Preservatives prevent contamination from bacteria or fungi. Small traces of manufacturing substances (such as yeast) may remain in extremely tiny amounts.
Some vaccines are stored as a powder and need to be mixed with a liquid before injection. Sterile water is commonly used for this purpose.
Common Vaccine Myths and Misconceptions
Myth: Vaccines cause autism or SIDS
There is no scientific evidence linking vaccines to autism or sudden infant death syndrome (SIDS). A 1998 study suggesting a link between the measles-mumps-rubella (MMR) vaccine and autism was later retracted due to flawed science.
Myth: Vaccines contain harmful heavy metals
Mercury is not used as a preservative in vaccines routinely given to children in Australia. Today, childhood vaccines are provided in single‑dose packaging.
Myth: Natural immunity is better than vaccine immunity
Natural infection can lead to immunity, but it also carries significant risks including severe illness, hospitalisation and death. Vaccines allow the immune system to build protection without experiencing the disease itself.
Myth: Vaccines overwhelm the immune system
Children encounter thousands of antigens every day. The number of antigens contained in vaccines is extremely small in comparison, and research shows receiving multiple vaccines at once is safe.
Myth: Doctors profit from vaccines
Medical clinics have many costs associated with providing vaccines, including refrigeration, storage, staff time, and equipment. Doctors recommend vaccines because they help protect children, families and the wider community.
Where to Learn More About Vaccine Safety
If you would like more information about vaccines and their safety, we recommend visiting the Melbourne Vaccine Education Centre (MVEC) website.
If you have questions about your child’s vaccinations, please feel free to discuss them with one of our doctors.
We are always happy to talk through any concerns and help you make informed decisions about your family’s health.
You can book an appointment at Sage Medical by:
📞 Call us on 03 8606 3206
🌐 Or click here to book online
