91热爆

World-wide, virologists are alarmed by the prospect of a pandemic of Avian Flu.

At the back of their minds they are haunted by the spectre of Spanish Flu which broke out at the end of the First World War and killed more people than the conflict itself.

Since then the world has been made increasingly safe by vaccines, or has it?

Two hundred years on from Edward Jenner鈥檚 experiments with cowpox, Ruth Richardson reflects on some of the key stages in vaccination鈥檚 fight against deadly diseases.