How vaccines work
Vaccines protect us by using our body’s natural defences to build resistance to specific infections before we come into contact with them.
When a child gets a vaccine, their body produces an immune response in the same way it would after exposure to a disease. If the child comes in contact with that disease in the future, their immune system remembers it and responds quickly, preventing the disease from developing.
Vaccines give protection without causing disease. They are safer than getting the disease itself.
Vaccination protects children against serious diseases that could lead to complications including disability and even death. By vaccinating your child you help protect other members of your family or community who are vulnerable, pregnant women, older people and people with health conditions. It is much harder for a disease to spread when many people in the community are vaccinated. This is called this herd immunity.
The benefit of herd immunity is we can protect those who cannot get vaccinated, including babies who are too young to get vaccinated or people who can’t get vaccinated for medical reasons.
Vaccines contain several ingredients including an antigen, which is a modified form of the virus, bacteria or toxin that causes the disease.
Other ingredients such as adjuvants, preservatives and stabilisers ensure vaccines are safe and effective, helping to strengthen the immune response, making them work better.
Vaccine ingredients can look unfamiliar as a list on a label. However, many of the components used in vaccines occur naturally in the body, environment and foods we eat.
All the ingredients in vaccines – and the vaccines themselves – are thoroughly tested and monitored to ensure they are safe.
Mercury is no longer used as a preservative in any vaccines routinely given to children in Australia. Before 2000, some contained thiomersal (a compound containing mercury) as a preservative in multidose packaging. Scheduled childhood vaccines under the National Immunisation Program come in a single dose package.
Yes, it is possible since no vaccine is 100% effective. Protection levels provided by vaccines differ, so a small number of people who do not develop immunity may still get the disease. They usually experience a less severe disease if they are vaccinated.
Yes, vaccines are safe. All vaccines go through rigorous testing to ensure they are safe and effective before approval in Australia by the Therapeutic Goods Administration (TGA). This includes various stages of clinical trials and testing of ingredients. Vaccines that don’t meet quality and safety criteria do not get approval and are not available for use. This forms part of a comprehensive process before listing vaccines on the National Immunisation Program.
Once available, their safety continues to be monitored with any concerns raised taken very seriously and investigated promptly. This is through reporting of adverse events to the TGA and national active monitoring through AusVaxSafety.
Vaccines protect people from serious infectious diseases that once harmed many infants, children, and adults and caused deaths every year. Without vaccines, your child is at risk of getting seriously ill and suffering ongoing complications, and even death from diseases like measles and whooping cough. While there are possible side effects of vaccination, these are almost always mild (redness and swelling where the needle went in) and disappear in a few days. Serious side effects after vaccination, such as a severe allergic reaction, are very rare.
It is safer to be vaccinate than get the disease. For example, tetanus could cause extreme pain, muscle spasms, and difficulty breathing. Measles could cause pneumonia or brain swelling.
No. There is no established link between vaccines and autism. The measles, mumps, rubella (MMR) vaccine doesn’t cause autism. High-quality studies and reviews over many years have compared the health of large numbers of vaccinated and unvaccinated children. The studies found no link between the MMR vaccine and autism. Scientific studies and reviews continue to show no relationship between vaccines and autism.
The suggested link between the MMR vaccine and autism was first published in 1998 in a research paper published in a respected medical journal.
Since then, scientists have completely discredited this paper based on only 12 children. In 2004, the authors retracted their claim of a link between vaccination and autism. In 2010, the journal withdrew the paper after the UK’s General Medical Council found the results in the paper had proved to be false. The journal issued a retraction.
Most of the side effects associated with vaccines are minor, and usually go away within a few days.
Some children might have common reactions such as:
- redness, swelling and soreness where the needle went in
- appearing grizzly, unsettled, unhappy and sleepy
- a mild fever.
These reactions show the immune system is interacting with the vaccine. This is normal. While these symptoms may concern you and upset your child at the time, they usually resolve quickly on their own.
To reduce fever or soreness after vaccination, you can use pain relief medicines, such as paracetamol, as directed.
Serious side effects from immunisation are very rare. There is a very small risk of a serious allergic reaction (anaphylaxis) to any vaccine. Anaphylaxis usually happens within a few minutes of vaccination, before you and your baby leave the clinic. This is why you are asked to stay at the clinic or medical surgery for at least 15 minutes following immunisation in case further treatment is required.
Your doctor or nurse knows what to do to help a baby having an anaphylactic reaction recover quickly.
If your child has a reaction that you think is severe or unexpected, seek medical advice straight away.
Yes. Giving babies and children several vaccines at a single visit is safe. Combination vaccines allow children to be immunised against more diseases with fewer injections. This means less pain and stress for the child.
For example, one of the vaccines given at 2, 4 and 6 months of age provides protection against 6 diseases, which means your baby is protected against 6 diseases by having this injection in a single visit. This is completely safe and will not overload the immune system.
Infants’ immune systems are very strong. Babies encounter many thousands of different types of antigens (parts of organisms that cause disease, such as bacteria or viruses). Vaccines contain only a very small number of antigens compared with the large number children encounter every day. Vaccines will strengthen your baby’s immunity to protect them from some of the most dangerous infectious diseases.
No. There is no evidence that vaccines cause or worsen asthma or allergies. It is important that children with asthma or allergies are vaccinated to reduce their chance of getting a serious infection, which could make their existing condition worse.
Some vaccines contain ingredients that can be allergens. So, if your child is allergic to any foods or medicines, you should tell your doctor or nurse so they can check that the vaccines they plan to give your child are safe.
Vaccine preventable diseases
Yes. The diseases that routine immunisation protect against can be serious and even fatal. We don’t hear much about them as they are no longer common due to the success of vaccination programs in Australia. However, If we don't vaccinate, the serious diseases will re-emerge in the community.
Childhood immunisations are needed to protect children, even if we don’t often see the diseases they protect against.
Some diseases are no longer common in Australia because of vaccines, such as polio, diphtheria and measles. If we stopped vaccinating, the few cases we have in Australia could very quickly become tens or hundreds of thousands of cases.
Even though many serious vaccine-preventable diseases are uncommon in Australia, some are common in other parts of the world, such as measles and polio. Even if your family does not travel internationally, you could come into contact with international travellers anywhere in your community.
Getting your child vaccinated can also help protect people who can’t be vaccinated through herd immunity.
Children get vaccines to protect them as soon as possible as they are at greatest risk from disease while they are very young. Even though babies’ immune systems are strong, vaccinations in early stages of life are vital because they protect babies while their immune system is still developing.
Babies are perfectly capable of tolerating vaccines, just like they handle the thousands of bacteria and viruses they encounter in their environment since the moment of birth. Immunisation can protect your child from serious infections that could lead to suffering, hospitalisation or even be fatal.
The schedule is different in other countries because patterns of disease, strains of viruses or bacteria, medical care, available vaccines and their costs vary from country to country.
Delaying or spacing out vaccines means children are unprotected for longer than need be, at an age when disease is most common or most serious. The first dose of a vaccine is recommended for the youngest age that a baby’s immune system is mature enough to give a good response and get good protection.
The timing of each dose of every vaccine given to babies and children is chosen with care based on many decades of research. It is best to follow the National Immunisation Program schedule and the due dates. Even if you’re just a few weeks late this puts your child at risk of contracting serious disease.
Spacing out vaccines would also mean that a child is likely to need more vaccination appointments and injections. This would mean more stress for the child. Research has shown that children experience just as much stress when they get one needle as they do when they get more than one.
Some children may need extra vaccines if they are at a higher risk of disease. Additional vaccines for certain groups are also available free under the National Immunisation program. This could be children with certain medical conditions that put them at greater risk of disease. Aboriginal and Torres Strait Islander children also have a higher risk of some diseases than non-Indigenous people.
Speak to your doctor about your child’s specific needs.
You can immunise babies and children with minor coughs and colds without fever, or babies recovering from an illness safely and effectively.
If a child is very unwell with a high fever (over 38.5 degrees Celsius) you should postpone the immunisation.
You can arrange an appointment a week or two later when your child is well again. If in any doubt, ask your doctor or health clinic staff before delaying immunisation.
On time vaccination offers the best protection. However if your child has fallen behind it is easy to catch up. There is no need to repeat the doses already received and there is no need to get extra doses. Talk to your immunisation provider about a catch-up program.
Under the National Immunisation Program, routine vaccines are free if your child is eligible for Medicare. Your doctor may charge a consultation fee.
Aboriginal and Torres Strait Islander children and children with certain medical conditions may receive recommendation to receive extra vaccines for free. Speak to your doctor, nurse or health care worker about your child's specific needs.
If you have more questions or want more detail to help you decide about vaccination, check out the following resources. Your doctor, nurse or health care worker can also give vaccination information for you and your family.
When looking online for vaccine information, be sure to use reliable sources based on scientific evidence.