The decreasing severity, but rising importance, of whooping cough

The death rate from whooping cough fell steeply in the 20
th century along with other diseases such as measles, diphtheria and scarlet fever as is shown on the following graph:

The number of deaths from all these diseases fell dramatically during the first half of the twentieth century before any vaccinations. By the late 1940s and 1950s, even though the number of whooping cough deaths was only a small fraction of what they had been fifty years earlier, a relatively brief stage was reached when the actual number of deaths from whooping cough (see orange arrow) was greater than from the other three diseases combined.

The spectacular fall in deaths from all these diseases was due to better nutrition, improved housing and smaller family size. As the Ministry of Health acknowledged in 1953, “the contributions made by improved therapy, such as the use of antibiotics, and by immunisation must, so far, have been comparatively small.”
1 However, by 1950 there was concern that whooping cough, though undeniably far less of a problem than before, was responsible for more deaths than any of the other common infectious diseases of childhood. After the apparent success of immunisation against diphtheria, it was time to look for a vaccine against whooping cough

1Thomson D. Monthly Bulletin of the Ministry of Health and PHLS 1953: 92-102