Vaccination and Immunisation

The immune system has a remarkable property: it remembers. Once your body fights off a pathogen, it keeps a stock of memory B-cells and T-cells that recognise that same invader instantly if it ever returns. Vaccination exploits this memory to give you protection without making you sick first.

A vaccine is a preparation that contains antigenic proteins from a pathogen, or the whole pathogen that has been inactivated or weakened. When this is introduced into the body, your immune system treats it as a real threat. It produces antibodies against those antigens, and it also creates memory B-cells and T-cells. Later, if the actual pathogen enters your body, those memory cells recognise it quickly and trigger a massive, rapid production of antibodies that overwhelm the invaders before they can cause disease.

Sometimes there is no time to wait for the body to produce its own antibodies. In cases like tetanus infection or a snakebite, the threat is immediate and deadly. Here, doctors directly inject preformed antibodies — antibodies that were already made outside the body. For tetanus, this preparation is called antitoxin (antibodies against the bacterial toxin). For snakebites, the injection contains preformed antibodies against the snake venom. This approach is called passive immunisation, because the body does not actively produce its own antibodies; it receives them ready-made.