Vaccine development

There are many pre-clinical stages of research before a vaccine for a disease can be developed. This research addresses questions including:

• Do humans normally develop protective immunity against the infection? This increases the chances of making a successful vaccine.
• Which proteins or carbohydrates in the microbe can immune cells respond to? Are there different versions of these proteins or carbohydrates in the microbe?
• Can the immune-stimulating components of the microbe be packaged in vaccine form, and delivered into experimental systems to stimulate immune responses?
• Do the immune responses prevent subsequent infection with the microbe, and how long does the protection last?
• How can large amounts of the vaccine be prepared in a consistent and cost-efficient way? A vaccine that is labour-intensive to make, or can only be made in small batches, may not be economically feasible.

If a vaccine shows promise in pre-clinical testing, it may enter clinical trials. These involve giving the vaccine to volunteers to test:

• The safety of the vaccine and highest dose tolerated.
• Whether people develop the expected immune changes after being given the vaccine.
• Whether people at risk of infection with the target microbe are protected by the vaccine.

These steps can take many years. If a vaccine is shown to be safe, and beneficial for protecting people against infection, it may be approved by government bodies for clinical use.

Depending on the prevalence and severity of the infection in a community, the vaccine may be recommended:

• For all people, such as measles vaccine, to restrict any transmission of the infection in the community.
• For people who are likely to be exposed to the infection. Cholera vaccinations for travellers visiting parts of the world where this disease is prevalent are an example.
• For people who are at high risk of serious illness caused by an infection that is less severe in most people. For example, people with chronic respiratory diseases are advised to have flu vaccines.

All vaccines available for use in humans are thoroughly assessed for safety by independent health authorities and researchers. Vaccines are only approved for use if they are proven to be beneficial in protecting against a potentially serious infection.

In some cases, rare side-effects can occur in a small number of people who receive a vaccine. These are typically less serious, and much less likely than potential side-effects of the infection the vaccine aims to protect against

When a vaccine is recommended for a person, it is because any risk of receiving the vaccine is outweighed by the risk of not being vaccinated and contracting the relevant infection.

The Australian Academy of Science’s The Science of Immunisation booklet provides scientifically valid answers to many of the frequently asked questions about vaccination and vaccine safety.

Usually vaccination refers to treatments that trigger immune responses. Some vaccines are being developed that switch off harmful immune responses.

An example is a nasal insulin spray developed by our researchers that is now in clinical trials for preventing type 1 diabetes in susceptible people. The treatment is being tested for its ability to turn off the harmful immune responses to insulin-secreting pancreatic cells that cause type 1 diabetes.