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amongst females of which five were paralytic. The age distribution of
the cases was two under five, four of 5-10 years, four of 10-15 years, two
of 15-25 and two over 25.
Cases occurred in all parts of the district and apart from the infection
of the two sisters, no case seemed to be associated with any other.
Inoculation. After controlled trials in the United States and other
countries had showed that the Salk type vaccine which was a pure culture
vaccine killed by formalin was eighty to ninety per cent, effective in
preventing paralytic poliomyelitis in inoculated children and was also
safe, the National Foundation of Infantile Paralysis made sufficient
vaccine available to inoculate some nine million school children in the
United States. The vaccine was prepared by a number of firms. The
trial started early in 1955. Unfortunately the use of the vaccine prepared
by one factory was followed by inoculation paralysis in a number of those
treated. The investigations carried out led to the detection of the weakness
in the process of manufacture. This was corrected and subsequently
large numbers of children were vaccinated, with none of these unfortunate
results. It had been decided that a trial of the Salk vaccine should
be made in this country in 1955. The American experience led to its
deferment. In the meantime those in this country modified their methods
of preparing the vaccine. One change was the use of a less virulent
strain of the type 1 virus, a change which would make the vaccine safer
while it was hoped not impairing its efficacy. Supplies of this vaccine
became available in the earlier part of the year and in March the Government
announced that the limited supplies then available were to be used
in the coming months. As supplies did not enable all those children
whose parents wished them done to be treated, selection had to be made.
It was decided to deal only with children of ages two to nine. In order
that a statistical analysis of the efficacy of the preparation in protecting
those treated could be carried out, the selection of children within those
age groups was determined by the Minister. It was in fact determined
by the month in which any child was born, the order chosen being March,
November, August and October. Supplies were made available in April
and children were treated in the two months May and June. The arrangements
were then discontinued because of the expectation that the incidence
of poliomyelitis would by then have become marked, and it would be
inadvisable to carry out the practice while the disease was prevalent
The material available was used under arrangements made by the local
health authority, there being not sufficient at the time to enable distribution
to be made to the general medical practitioners. The parents of the
children of the selected ages were told of the arrangements by means ot
letters sent out from the schools in the case of school children, other
notices at the clinics and some information in the press. 7,186 requests
were received by March 24th, the local closing date, a proportion much
the same as that in the county and slightly above that of the country as a
whole. Inoculations were started at the beginning of May, these being
carried out at ordinary clinic sessions, or at special sessions held at the
clinics. The material made available for children in this district enable
some 700 children to have the two doses and a small number to have the
first doses only. The first 75 children treated were visited one wee