Modern heroes

The great achievements of vaccines are not consigned to the past. It is easy to see the heroic age of vaccines as one that ended decades ago. The Salk polio vaccine, after all, which swiftly and visibly transformed the disease into a distant memory in the developed world, was introduced in 1955. And the smallpox eradication campaign led by the World Health Organization had, by the late 1970s, reduced the virus from a killer of millions of people a year to a prisoner of biosafety labs. These were monumental feats, but the best could be still to come. Worldwide, up to one-third of all deaths of children under five result from diarrhoea and pneumonia. In the past ten years or so, vaccines against the microorganisms that cause many of these cases have become a standard part of the childhood regimen in the developed world. If they could be made available worldwide,...