How the immune system works
The first time you’re exposed to a virus or bacteria, the immune system can be slow to make antibodies. That’s because it doesn’t recognise the virus or bacteria. While your immune system is making new antibodies, the virus or bacteria multiplies and spreads throughout your body. This is what causes disease symptoms – for example, fever, cough or rash.
Once your immune system has produced antibodies, it starts to destroy the virus or bacteria. And you start to recover from disease symptoms.
If you’re exposed to the same virus or bacteria again, your immune system can respond quickly because it remembers how to produce the right antibodies. And this means you get only mild disease symptoms or no symptoms at all.
How vaccines give you immunity
Vaccines boost your immune system’s ability to fight viruses or bacteria, but you don’t have to get the viruses or bacteria first.
Vaccines also contribute to herd immunity. Herd immunity is when enough people in the community are protected from a disease, so the disease spread slows down or stops. Herd immunity helps to protect babies who are too young to be immunised and people who are more likely to get sick, including people with other serious illnesses and elderly people.
Vaccination versus infection
Children and babies: vaccine needs
Babies and young children get many vaccines through the National Immunisation Program. The best time to get a vaccine is before you’ve been exposed to an infectious disease, so that’s why children get so many vaccines during childhood.
Pregnant women: vaccine needs
Adults and children with weakened immune systems: vaccine needs
Adults and children with allergies: vaccine considerations
Older people: vaccine needs
If a person can’t be vaccinated, it’s important for the people around that person to be vaccinated. This can give the person some protection from disease by reducing their exposure to disease.
Getting advice about vaccines
There are specialist immunisation services in most states and territories. These clinics are for children who’ve had adverse reactions to vaccines in the past or who are in high-risk groups, or for families who are concerned about vaccinating their children. You usually need a referral from your GP or specialist to go to one of these clinics.
Vaccines, vaccination and immunisation
You might hear the terms vaccine, vaccination and immunisation:
- A vaccine helps protects you from a disease. It’s a medicine.
- Vaccination means actually getting the vaccine, either by mouth or through injection.
- Immunisation means both getting the vaccine and being protected from the disease.
Most people use ‘vaccination’ and ‘immunisation’ to mean the same thing, although they’re not quite the same.