How does a vaccine work?
Vaccines work by introducing into the body a bit of deactivated (no longer dangerous) disease virus or bacteria. And then the body’s immune system says, ‘Oh, no you don’t! You look like a dodgy intruder!’ and starts producing antibodies – defences to the disease – without being threatened by the disease itself. When your kid’s body encounters the germ again later in life, their immune system is able to say ‘Oh, ho! Not you again! I already know how to keep you out.’
Other bits inside vaccines include a preservative (no mercury or mercury-like substance is used for this in any Australian childhood vaccines), a sugar ‘stabiliser’, sterile water, the relevant germ, and the relevant compound to make sure the germ isn’t ‘active’. Vaccines are not ‘full of toxins’.
A new vaccine is first tested on laboratory animals, then larger animals, then finally on human adult volunteers first. This process takes many, many years. Results are then reported, published and checked by government licensors before a vaccine is released for medical use in kids.
There’s much more on vaccines and immunisation, and what they protect your baby from, in the book Babies & Toddlers: The Sequel to Up the Duff.