Smallpox

Smallpox and its Eradication @ World Health Organization 1988

Introduction

For more than three thousand years, smallpox was a major scourge of mankind, spreading across the world as new centres of population became established and grew in size. Because of its high fatality rate, it was universally feared; in the towns and cities of Asia and Europe where records were kept, it caused on average 10% of all deaths each year.

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In the early 1950s, 150 years after the introduction of vaccination, there were probably some 50 million cases of smallpox in the world each year, a figure which had fallen to perhaps 10-15 million by 1967, when the disease had already been eliminated in 125 of the 156 countries and areas listed in the legend of Fig. 4.1.

That's still about 2 million deaths a year.

p272 Evidence for the Efficacy of Vaccination

The figures for Sweden, which has some of the earliest reliable statistics, are shown in Fig. 6.1. Vaccination began in Sweden late in 1801 and was made compulsory in 1816. From about 1802 onwards there was a dramatic change in the 18th century pattern of major epidemics (3000-7000 smallpox deaths per million population) every 5 years or so, against a background of high endemicity (600-800 smallpox deaths per million population). The epidemic waves subsided and from about 1810, as vaccination became more widespread, the figures fell to unprecedently low levels. Six years after the institution of compulsory vaccination the ratio of smallpox deaths per million population reached a single figure-over a hundredfold reduction from the ~revious endemic level. After that, in spite of the maintenance of a reasonably high level of infant vaccination, the death rate rose again and epidemics recurred, although at a tenth the amplitude and at longer intervals than in the 18th century.

(the key to further reduction was revaccination)

A few years later Edwardes (1902) published his compendium of statistics. All investigations illustrated that the practice of vaccination and revaccination, properly conducted, was a brilliant success; Jenner's prediction (see Plate 6.8) that smallpox could be eradicated by vaccination was correct. Almost 80 years were to elapse, however, before global eradication was achieved, and practices additional to mass vaccination, which in an elementary form had antedated the concepts of variolation and vaccination, had to be invoked-namely, isolation and containment.