London's Pulse: Medical Officer of Health reports 1848-1972
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Hints from the Health Department. Leaflet from the archive of the Society of Medical Officers of Health. Credit: Wellcome Collection, London
Walthamstow 1960
[Report of the Medical Officer of Health for Walthamstow]
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12.
Two interim reports have already been published and
these have shown quite clearly the effectiveness of the
vaccine. During the first five years of the trials the
incidence of tuberculosis in the vaccinated group was only
0. S8 per thousand, whereas it was 2.30 per thousand in the
unvaccinated control group. This means that the risk of
infection in the unvaccinated was six times greater than in
the vaccinated. Similar results were shown in the 5 to Hi
year period of the trials. Thus we confidently expect a
great degree of protection for at least 7% years subsequent
upon vaccination, these also being the most valuable years
of adolescence.
Freeze-Dried B.C. G. -
A trial of the British Freeze-Dried B. C. G. Vaccine
was undertaken at the request of tne County Medical officer,
and Dr. G.H.G, Poole has contributed the following report -
" It was unfortunate that the bulk of the B. C. G.
programme for the year had already been completed so that
relatively few children were available to take part in the
trial. However, a comparison has been made between the
results obtained from the Danish Liquid Vaccine in 349
children with those of Freeze Dried in 291.
" The following table gives the conversion to the postvaccination
Heaf Test.
TABLE I
| Heaf I No. % | Heaf II NOi % | Heaf III No. % | Heaf IV No. % | Neg. NO. % | Abs. | Total | |
|---|---|---|---|---|---|---|---|
| Liquid (at 6/52) | 183 62.3 | 101 34.3 | 7 2.4 | - | 3 1.0 | 55 | 349 |
| Freeze (at 6/52) | 121 92.4 | 10 7.6 | - | - | - | 23 | 154 |
| Dried (at 5/12) | 15 11.8 | 82 64.6 | 30 23.6 | - | - | 10 | 137 |
| TOTAL | 136 52.7 | 92 35.7 | 30 11.6 | - | - | 33 | 291 |
"Because of the local diphtheria outbreak the 137 in
line 3 above were not post-B.C.G. Heaf tested until five
months after vaccination instead of the normal six weeks
and this delay appears to have been associated with an
increased reaction to tuberculin, e.g. at six weeks over
90 per cent gave a Stage I response only, while at five
months two thirds of a similar group gave a Stage II and
nearly a quarter a Stage III response.
" I do not know whether this progressive response would
occur with the liquid vaccine also since our tests on this
were all at the six weeks interval. If this effect occurs
only in freeze dried vaccine it may be due to the depot
effect resulting from aggregations of undispersed bacilli
unless there is some antigenic difference between the
strains or some mutant effect induced by the freeze drying
process.