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It will be seen that out of 64 cases notified as paralytic six proved to be non.paralytic
or not poliomyelitis and that, out of the 23 cases notified as non.paralytic, three proved
to be of the paralytic form and five were not poliomyelitis. Thus, on balance, the original
notifications slightly overstated the extent of the paralytic form—64 against 61—and there
were 10 cases which proved to be not poliomyelitis. The vaccinal state of the 61 cases
finally diagnosed as paralytic poliomyelitis and the 16 non.paralytic cases is set out in
table (xviii).

* Two or three injections.
It is estimated that at 30 June, 1960—about midway point of the poliomyelitis season
in 1960—70 per cent, of children aged 0.14 years had received two injections of poliomyelitis
vaccine. Applying this percentage to the child population at risk gives the following
incidence rates for the paralytic form of the disease:
Cases per 1,000
Population Cases* population at
0.14 years risk
Vaccinated 451,000 5 0.011
Not vaccinated 193,000 39 0.202
* Excluding two cases vaccinal state not known.
Thus the incidence rate in the unvaccinated children was about eighteen times that in
the vaccinated: even if the two cases in which the vaccinal state was not known are included
in the figure of cases among vaccinated children (which is doubtful) the differential in the
incidence rates becomes thirteen times.
In similar previous analyses the corresponding differential between incidence rates in
the unvaccinated and vaccinated was, for the last six months of 1958, five times and for
the year 1960 seven times. The greater difference in the incidence rates in 1960 may be
linked with tne fact that by the end of that year about three.quarters of the vaccinated
child population had received a third injection of vaccine compared with one.half at the
end of 1959.
Smallpox—There was one case notified during the year in the City of Westminster; this
was in respect of a visitor to this country. Fortunately no secondary cases resulted.
Whooping cough—After the low figures of recent years there was a considerable increase
in the notifications of whooping cough, the heaviest incidence being during the summer
months. In spite of this increased incidence mortality remained gratifyingly low.
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