Which one of the following statements regarding immunisation is true?

The statement regarding immunisation that is true is that living microorganisms may be used to provide immunity. This approach is known as live attenuated vaccination, where a weakened form of the pathogen is used to stimulate an immune response without causing the disease in healthy individuals. This type of vaccination can lead to a strong and often long-lasting immune response because it closely mimics a natural infection.

Immunisation strategies vary significantly among vaccines. While some may provide lifelong immunity, such as those for measles, mumps, and rubella, not all vaccines guarantee this level of protection. Certain vaccines might require booster doses to maintain immunity over time. Furthermore, Hepatitis C does not have a vaccine available for prevention, which makes the statement about it being preventable through immunisation incorrect. Additionally, vaccination typically aims to induce artificial immunity rather than natural immunity that occurs through actual infection. Therefore, the use of live microorganisms in some vaccines stands out as a key mechanism in achieving immunity.