Immunisations work on the same kind of principle that by injecting a very small amount of the disease – so small or inactive that it will not give you the disease itself, a person will develop antibodies and therefore an immunity to the disease and are very, very unlikely to suffer the disease itself, or if they do, it will be in a very mild form. Over the years many vaccines have been developed against infectious diseases. These vaccines contain either minute quantities of the active disease or contain the bug giving the disease in a very modified form so that it means that your body creates the antibodies that you need but that you don’t actually get the disease itself. In this way you get all the protection that you should have without having the illness.

Safety is always the primary concern in designing a vaccine, and is the first thing that is tested when a new vaccine is going through clinical trials. All potential problems of any kind are thoroughly investigated and excluded before clinical trials are started on children. Side effects are studied in the clinical trials, often by parents keeping diaries of their children’s symptoms after vaccination – if there are any. By the time that a vaccine is ready to be given routinely to all children, there will be evidence of the vaccines safety from studies involving tens of thousands of children, and this evidence will have been examined extremely carefully by national and international drug safety committees. For more information on the safety of vaccines have a look at the ‘Questions and Answers’ section on this site.

As well as containing a very small amount live or modified amounts of the bugs causing the disease, vaccines are also preserved with small amounts of things such as formaldehyde, aluminium and antibiotics. Formaldehyde converts the bacterial toxins into toxoid which are harmless but give immunity against the dangerous toxins which may be produced when you actually get the bad form of the infectious diseases. This is an entirely safe procedure which really works. Also every batch of toxoid vaccines is tested to make sure that they have been made absolutely safe, and that the preservatives in the vaccines are in very, very low dosages.