How does immunisation work?
All forms of immunisation work in the same way. When a person is vaccinated, their body produces an immune response in the same way their body would after exposure to a disease, but without the person suffering symptoms of the disease. When a person comes in contact with that disease in the future, their immune system will respond fast enough to prevent the person developing the disease.
How long do immunisations take to work?
In general, the normal immune response takes approximately two weeks to work. This means protection from an infection will not occur immediately after immunisation.
How long do immunisations last?
The protective effect of immunisations is not always for a lifetime. Some can last up to 30 years while others may only last four years. Due to frequent changes to the influenza virus, annual influenza vaccination is needed to provide protection against the most recent virus.
Is everyone protected from disease by immunisation?
Even when all the doses of a vaccine have been given, not everyone is protected against the disease. Booster doses are needed because immunity decreases over time.
How safe are vaccines?
All vaccines currently available in Australia must pass stringent safety testing before being approved for use by the Therapeutic Goods Administration. This testing is required by law and is usually done over many years during the vaccine’s development. In addition, the safety of vaccines is monitored once they are in use, by the Advisory Committee on the Safety of Medicines and other organisations.
Before vaccines are made available for use they are rigorously tested in thousands of people in progressively larger clinical trials. These trials are strictly monitored for safety. The approval process can take up to 10 years. As a result of such detailed testing, a number of vaccines that failed in these early tests have never been released.