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"3. The M.R.C. Mantoux dose was 100 units, not 10 units as in our cases.
It is generally agreed that Mantoux testing with 100 units probably gives a few
false positives.
"4. Most of the positives might be expected to be among contact cases,
and most known contacts had already been vaccinated in Leyton, and in any
case were not invited to apply for vaccination as school leavers.
"Of a proportion of the number of vaccinated (183) only one case failed to
convert and has been re-vaccinated. Six others were negative when first re-tested
after vaccination but either converted late or were more sensitive to the old
tuberculin (10 units) with which they were re-tested than they had been to the
P.P.D."
RESEARCH WORK
Anti-tuberculosis Vaccine (B.C.G.).
In collaboration with the Medical Research Council, there is still being
undertaken in Leyton schools the investigation into the efficiency of B.C.G.
vaccine to which reference was made in my last Annual Report.
The trial involved at the outset children leaving Secondary Modern
Schools at the age of 15, and it was proposed to follow them up by regular
examinations for at least three years. Participants in the trial were volunteers.
The trial is still going on, and the results will not be available for some
time. The following observations on its progress are submitted by Dr. T. M.
Pollock, Physician-in-Charge.
" The investigation into the efficacy of Anti-tuberculosis vaccines, in which
Leyton Public Health Authority is co-operating with the Medical Research
Council, continued during 1954. It is hoped to determine the degree and duration
of protection afforded by vaccination, and thus the contribution which the vaccines
can make to the prevention of tuberculosis in young people.
"Over 50,000 volunteers from North London Boroughs, as well as from areas
in Birmingham and Manchester, joined the scheme during their last terms at
school between 1950 and 1952. Some of the volunteers were given the vaccines,
and all who entered the scheme are now being followed up. 628 volunteers
joined in Leyton, and during the year many of them were visited by the Health
Visitors. The Medical Research Council's Mass X-ray Unit visited Dawlish
Road Clinic during May, and three-quarters of the volunteers invited, attended
for X-ray.
"Co-operation between the Leyton Public Health Authority and the Medical
Research Council, in all matters relating to the investigation, was very close
throughout the year."