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8
Incidence
upon
children of
elementary
schools,
i.) Effect on
school
attendance.
ii.) Incilence
upon
children of
selected
schools.
Mortality in
metropolitan
Doroughs.
mortality
??? large
owns of
England
and Wales.
incidence of deaths certified to influenza, would not be materially modified by the inclusion of the
estimated influenzal deaths classified to pneumonia, bronchitis, etc.
The effect of the summer epidemic upon the attendance of school children was remarkable, the
reduction in the percentage attending schools indicating a greater proportion of cases among children
than among working adults, so far as the incidence upon the latter can be judged from the sickness rates
available. The figures for the twelve school divisions of the county show that the districts most affected
in the summer suffered proportionately less in the autumn, and that the total reduction in attendance
for the two epidemics together was not very greatly different in the twelve divisions. This points to
the conclusion that a certain definite and fairly constant proportion of the children in each division
was susceptible to infection, and that those susceptible children who escaped infection in the summer
succumbed in the autumn. No doubt the range of personal contact is greater at the school age than at
any other period of life mainly owing to the scramble of play which, it may be remarked, is not much
affected by school closure: thus it may reasonably be assumed that in the course of one or other of
these two epidemics almost every child 'was exposed to infection. The resulting exhaustion of the
"susceptibles" would account for the relatively small effect upon the school attendance of the winter
epidemic. Much, indeed, of the reduction in school attendance occurring during the early weeks of that
epidemic should rather be attributed to the severe weather than to the effect of illness. In the week
of maximum influenza prevalence, the school attendance percentage for London was 85-1 as compared
with 89 -4 when the schools opened at the beginning of the year, a fall of only 4-3. In the summer epidemic
the maximum, reduction was 15 4 and in the autumn 19 6. The deaths at ages 5-15 in the three epidemics
were 75, 1057 and 109 and as the approximate ratio of school weeks lost in the three epidemics was as
4 : 9 : 3 it appears that the case mortality in the winter was far below that of the autumn and about
twice that in the summer.
Enquiries were made by the school doctors into the incidence of influenza upon the pupils
attending the schools under their charge. Particular trouble was taken to ascertain the percentage of
children in the higher standards who were attacked, separating those suffering in the summer from
those attacked in the autumn. The figures which have thus been obtained relate to about 5,000 children
attending the three upper classes of 48 departments scattered over London. The percentages of boys and
girls attacked are set out separately. The enquiry was limited to children attending Standards V.,
VI. and VII., as more reliance can be placed upon information obtained from these children than
from those in lower forms and in infant departments.
The freakish behaviour of influenza, in general, repeats itself in its behaviour in the schools and
strange exceptions show themselves to almost every broad deduction made. It will be noticed that the
percentage of boys attacked varied from 10-5 in Holland-street school to 43-5 in Bonner-street school,
and the percentage of girls ranged from 14 in Bromley Hall-road to 62 in Alton-street school. The
average incidence upon the school population lay between 30 and 40 per cent., in general, being higher
on girls than boys.
Particular enquiry was made into the previous health of children who died from influenza and
schools were as a rule selected for investigation in which deaths had been reported. It appears to have
been the general experience that those children who died were either debilitated beforehand or had been
away from school previously for some serious ailment other than influenza.
A few cases were noted in which children suffered both in the summer and the autumn but they
form an infinitesimal percentage of the whole. The children, being in Standards V. to VII., are mainly
of higher school age, at which the excess in incidence in the autumn as compared with the summer, was
not so marked as at ages between 2 and 10 years. Nevertheless, generally speaking, the figures show
that where the percentage attacked was relatively low in the summer the autumn cases were proportionately
higher and vice versa.
The mortality in the various metropolitan boroughs varies broadly with the general death-rate
and infantile mortality, both of which depend mainly upon the social condition of the populations
concerned.
There are, however, certain points of contrast between the mortalities of the summer and the
autumn epidemic and these are best exemplified by figures relating to representative groups of boroughs
of the better class and the poorer class of population. It is found that in the summer the mortality
in the poorer class attributable to the epidemic was four times that of the better class group, but in the
autumn the ratio was only four to three. The conclusion is that populations suffering a relatively
heavy summer mortality were proportionately spared in the autumn epidemic, and secondly that the
total mortality in both epidemics was conditioned by the social class of the population.
The total mortality of the summer and autumn epidemics in the large towns appears, as in London,
to be broadly governed by the general death-rate and infant mortality of the town, but these rates are
of course controlled by many other factors than social condition, which it is difficult to standardise when
different large towns are compared. In Rhondda Urban District, Huddersfield and Middlesbrough, the
summer mortality was exceptionally high, but these towns had proportionately reduced mortality in the
autumn as compared with other towns. Elsewhere, as in Southampton, Swansea and Cardiff, a relatively
light summer mortality was succeeded by a proportionately greater autumn death-rate.
On the whole, a general consideration of the estimated total mortality caused by the summer and
autumn epidemics leads to the tentative conclusion that in each locality a certain proportion of the
population was liable to fatal attack, and the number of those succumbing in the autumn was in large
measure determined by the number escaping the summer epidemic without attack.
In judging of the severity of type of the disease in the two epidemics, much reliance cannot be
placed upon conclusions based upon mortality-rates alone, since it is possible that in one locality nine-