In London there were in 48 years of the seventeenth century no
less than 10 epidemics of smallpox; in the whole of the
eighteenth, 19; and in the nineteenth no epidemic at all during
which smallpox was responsible for more than one tenth of the
deaths from all causes in any one year.

In Sweden, the highest death-rate before vaccination was 7.23
per 1,000 persons, the lowest 0.30; under permissive
vaccination the highest was 2.57, the lowest 0.12; under
compulsory vaccination the highest was 0.94, the lowest 0.0005.

It is so frequently said that the disappearance of smallpox is
due not to vaccination, but to improved general hygiene, that
we must look into this criticism with some care. In the first
place, a large diminution in the mortality from smallpox
occurred before there was any great change in the unsanitary
conditions of the English towns, before there was any enforcing
of the isolation of patients either in hospitals or in their
own homes. Since the introduction of vaccination, measles and
whooping cough still remain in the status quo ante, while
smallpox has been exterminated in all fully vaccinated
communities, these two diseases of children are as prevalent as
ever in England even although the general sanitary conditions
have been immensely improved in that country. Of course the
effects of vaccination wear out in time, and that is why it is
well to be revaccinated once or twice. Now there has been a
remarkable progressive change in the age-incidence of smallpox
"which can only be explained," says Dr. Newsholme, "on the
assumption that vaccination protects children from smallpox and