A vaccine is a training exercise for your immune system, a way of acquiring the memory of an infection without the danger of having one. We look at what is actually in a vaccine, why some need boosters and others last a lifetime, how mRNA vaccines differ from everything that came before, and what herd immunity really means mathematically.

You'll come away understanding the difference between the main vaccine types, why effectiveness figures are so often misread, and why some diseases have been eradicated while others keep coming back.

Talking Science is sponsored by Kinsoft. Visit www.kinsoft.com.au

Further reading: World Health Organization immunisation pages; Australian Immunisation Handbook; Nature Reviews Immunology.