During an exchange with journalist Barrie Cassidy on the ABC television program Insiders, One Nation leader Pauline Hanson suggested there are tests available to see if children will have an adverse reaction to vaccinations.
HANSON: Barrie, some of these - parents are saying - vaccinations have an effect on some children. Go and have your tests first. You can have a test on your child first ...
CASSIDY: Take advice from the doctor.
HANSON: Have a test and see if you don't have a reaction to it first. Then you can have the vaccination.
It's not clear what kind of test Hanson was referring to. The Conversation asked three experts for more information.
Immunisation programs prevent millions of deaths worldwide each year. Vaccine safety monitoring – what experts call vaccine pharmacovigilance – as well as many other checks and balances before and after vaccines registration, ensure that vaccines have a minimal risk of causing harm.
Almost all vaccine side effects are mild and short lived. Common reactions such as low grade fever or pain at the injection occur in about one in every 10 children and go away within a day or two. Such reactions are evidence of our immune response to vaccines and a small trade-off for protection against serious diseases.
In most cases, we can't predict which person will be the one in a million to have a potentially more serious reaction after a vaccine.
There is no blood test to see if vaccines shouldn't be given. In fact, the best "test" for a deciding if a vaccine is appropriate is taking a good old medical history.
Pre-vaccination screening involves the nurse or doctor asking the patient a series of questions. It is done to ensure any conditions for which vaccines should or shouldn't be given are noted.
For example, pregnant women should not receive live attenuated vaccines (meaning vaccines derived from disease-causing pathogens that have been weakened in the lab) such as MMR (measles-mumps-rubella) vaccine. That's because there is a potential risk of rubella virus infection in the foetus.
However, they should have the inactivated pertussis (whooping cough) and influenza (flu) vaccines to protect both themselves and their newborns against these diseases.
People who have a compromised immune system, due to a medical condition or treatment, should not be given live vaccines. This includes elderly people who need their medical history checked carefully prior to administration of the live attenuated Zoster or "shingles" vaccine.
Vaccines should be used in the correct way: nurses and doctors who administer them have to have proper training. There is also extensive guidance for healthcare workers, who must update their knowledge each year.
The National Centre for Immunisation Research and Surveillance (NCIRS) works with the Australian Technical Advisory Group on Immunisation and others who support the National Immunisation Program to update the Australian Immunisation Handbook regularly to support this.
Parents take risks all the time because of the benefits of their action. We put babies in car seats, we let them play in playgrounds, and we vaccinate them. Vaccines are hugely beneficial but they are like any medicine: there are some rare but well-documented risks.
One is anaphylaxis, a life-threatening allergic reaction that occurs within minutes in about one in 1 million people. This risk is why patients are observed for 15 minutes after immunisation – if an anaphylactic reaction does occur, adrenaline is available to fully treat it.
Specific clinical assessment can help to differentiate if the cause was a vaccine ingredient or something coincidental – such as the peanut butter sandwich or aspirin taken shortly after the vaccine.
Causation versus correlation
Some problems previously blamed on vaccines have been found to be caused by other things.
For example, research into the human genome has helped disprove a link between vaccines and at least one serious condition. Dravet syndrome is a severe incurable form of epilepsy due to a genetic change that affects nerve cells.
The condition was previously associated with vaccines because the seizures appear in the first months of life in previously healthy babies, and are often triggered (but not caused) by fever. If a vaccine caused the fever, it appeared that vaccination caused the syndrome. It didn't.
Unfortunately, other conditions that become apparent in children in the first 12-24 months of life, such as autism spectrum disorder, have also wrongly been blamed on vaccines. In the case of autism, dozens of high quality studies and reviews over more than 15 years have shown absolutely no link to vaccines.
Personalised medicine is beginning to help understand disease at the individual patient level, such as by customising treatment based on the genetic make-up of a person's cancer. Gazing into the future, we may eventually learn more about what can predict both reactions as well as good responses to vaccines.
However, right now, the benefits of immunisation for children, adults and communities in eliminating or controlling some of the worst infectious diseases worldwide are clear.
This article first appeared on The Conversation.