Antibiotics

Antibiotics are medicines used by doctors when harmful microbes have made you ill. They are substances that harm bacteria. Some antibiotics stop the bacteria reproducing and others kill the bacteria directly.

Antibiotics are helpful to treat diseases caused by bacteria, such as tuberculosis and food poisoning. They do not harm viruses, so antibiotics cannot treat diseases such as colds and flu, which are caused by viruses.

Immunisation

Immunity

When you are infected by a microbe, it takes time for your body to start fighting the infection. It does this by making enough white blood cells with the correct antibody. During this time, you continue to feel unwell.

You begin to recover when enough antibodies have been produced. After the microbes have been killed, the amount of antibodies goes down again. But some of the white blood cells that produce the correct antibody remain in your blood.

After a second infection by the same microbe, your body makes the correct antibodies much faster, because of the white blood cells that remain from when you had the first infection. The microbe doesn't get a chance to make you ill this time, and we say that you are immune to the microbe and the disease it causes.

Check your understanding of this by studying the animation.

Vaccination

Immunisation is a process that doctors use to make people immune from certain illnesses, even before they have been infected. It involves you receiving an injection containing a vaccine.

Vaccines contain a dead or weak form of the disease-causing microbe, or some of its antigens. In response to the vaccine your immune system produces white blood cells with the correct antibody to kill the microbe, so you become immune without falling ill.

You are likely to have been immunised against several microbes, viruses and bacteria, including the ones that cause diphtheria, whooping cough, polio, tetanus, meningitis, measles, mumps and tuberculosis. Girls are also immunised against rubella.