Small Pox vaccine Smallpox vaccine poster. ©Edward Jenner Museum.

By Professor Brian Greenwood FRS
Department of Infectious and Tropical Diseases

What is a vaccination?

A vaccination is a stimulant to the body’s immune system that makes protective proteins (antibodies) and cells (lymphocytes) by administering a harmless organism or part of a harmful one. Once discovered, the foreign agent is destroyed and the immune system is prepared and more able to fight off future infection.

How many vaccines are there and do we need more?

Currently there are about 20 vaccines in common use. Research continues on the many serious infectious diseases (such as malaria and HIV) for which there are no vaccines. Research is also taking place on the development of new methods of giving vaccines (such as needleless injections) and on making vaccines that do not need to be kept in a fridge – presently this is a huge constraint on their use in the developing world where they are needed most. 

Is vaccination dangerous?

Although most vaccines can cause serious side effects, they occur very rarely and the benefits far outweigh the risks. Unjustified concerns about the MMR vaccine led to a drop in measles vaccination and outbreaks of measles, a potentially fatal infection, in several countries including the UK. All new vaccines are tested very carefully before they are licensed for general use.

When was vaccination discovered?

The principle underlying vaccination was first established by  Edward Jenner when, in 1796, he injected eight-year old James Phipps with material obtained from an animal with cowpox, an infection that is harmless in man, and showed that this protected James against smallpox, a potentially fatal infection.