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19
Over ten thousand swabs were taken, representing a tremendous
volume of work for the Public Health Laboratory as well as for
my own staff, who worked at high pressure and put in a good deal
of voluntary overtime.
Conclusions
This outbreak has demonstrated that a virulent strain can
cause a widespread infection even when 70% of the community are
immunised. The small number of cases prevents a statistically
valid comparison, but it is striking that of the infected
children who developed the disease only one in five had been
immunised, while of those who did not (the carriers) four out
of five had been immunised.
The comparatively high index of immunisation (70%) among the
children at risk was undoubtedly responsible for the occurrence
of only five cases in the presence of over seventy infected
persons, while the policy of concentrating on the early identification
and prompt removal to hospital of all carriers reduced
the infective pool. This was made possible only by the ready cooperation
of the Public Health Laboratory Service and the
admitting hospitals (St. Ann's, Honey Lane and the Eastern
Hospital) as well as by the head teachers and staff of the
schools concerned.
Most of the parents of infected children were quite co-operative,
but some were the reverse. One parent withdrew her children from
one hospital without clearance and put up a tremendous resistance
to proper control at home. Eventually she and her four children
were all admitted together to another hospital. Suggestions and
demands from parents varied from closing the schools to swabbing
the entire adult population of Walthamstow.
The decision not to close the schools was, in my view, amply
justified by the limited amount of spread which occurred in the
schools where the children were kept under surveillance and
repeatedly swabbed to exclude carriers. No school spread occurred
from Case 1, who infected, or was infected by, his sister (Case
2) or his aunt.
Case 3, a class-mate of Case 2 who developed the disease ten
days later, was presumably infected by the same source, possibly
at school, case 4, the pre-school child, was undoubtedly
infected by her brother, while in Case 5, the only one at the
infants school, no definite source was incriminated.
In favour of the occurrence of spread in the home rather than
at school is the fact that whole families became carriers. In
one family a parent and five children were infected, and in three