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13.
"Unfortunately the numbers available are unsufficient
to even out chance variations in susceptibility or
technique. Thus the liquid vaccine,with 34 per cent Stage
II conversions against less than 8 per cent Stage II
conversions (at six weeks) by the freeze dried,would
appear to be the stronger vaccine, yet it gave three
failures (approx. 1 per cent) against none for the freeze
dried. If lines 1 and 3 are compared the freeze dried
gives a higher degree of response in all cases but, as
explained above, this may be due to the longer interval
since vaccination.
" As a check on the homogenity of the suspension a
note was kept of the response to each successive dose
from each ampoule. The result is given below and appears
to indicate a uniform suspension of viable bacilli.

"Certain practical difficulties were experienced with
the new vaccine. It was rarely possible to obtain ten
doses from one ampoule (Danish vaccine gives ten plus)
and requirements were based on an estimated 7-8 doses per
ampoule. The vaccine, due to the contained dextran, is
sticky and less pleasant to use. It leaves a sooty
deposit on the platinum needle after flaming. Frothing
does occur but if the estimated quantity of vaccine is
pre-mixed before the session begins settlement soon
occurs and re-mixing in the syringe prior to use does not
cause frothing if carefully done.
" The sooting up and frequent change of needles is
the chief drawback to this vaccine in my experience and I
consider this is easily out-weighed by the advantage of
having vaccine always available so that the programme of
B. C. G. vaccination is made so much more flexible."