Onwards and upwards

VACCINES are medical science's nuclear weapons. Clean water and sewage disposal aside, they have saved more lives than any other public-health measure. Vaccines have wiped smallpox, a disease once dreaded by rich and poor alike, from the face of the Earth. They may soon do the same to polio. They have driven words like diphtheria and whooping cough from public discourse in rich countries, and might do the same for measles, mumps and rubella were it not for the vanity, selfishness or foolishness ...