Vaccination

technology · earth · Global

The deliberate induction of immunity by exposure to an attenuated, killed or antigenically related agent. Edward Jenner's 1796 demonstration that cowpox protected against smallpox gave the technique its name and its first practical form, but the transformation of mortality came much later, with the twentieth-century childhood schedules against diphtheria, pertussis, tetanus, polio, measles and, latterly, pneumococcus, rotavirus and Haemophilus influenzae type b. Vaccination is the only human intervention that has ever driven a pathogen to extinction in the wild: smallpox, declared eradicated in 1980, is the sole complete case, and rinderpest in cattle the sole veterinary one. Its contribution to life expectancy is concentrated almost entirely in the first five years of life, which is precisely why it moved the headline statistic so far while leaving the age at which old people die essentially untouched.