|FREEZE-DRIED BCG VACCINE SEALED IN PRESENCE OF NITROGEN
|Kul Bhushan, GVJ Baily, SS Nair, KT Ganapathy &
Vijay Singh: Indian J Med Res 1975, 63, 1335-43.
The Freeze-Dried BCG vaccine manufactured in India
is sealed under vacuum. This though adds to its stability involves
expensive production procedures. Sealing in presence of nitrogen
is both simpler and economical. Before producing this vaccine for
use on a large scale, it was considered necessary, to study the
influence of storage at higher temperatures on the allergy inducing
capacity on the basis of the size of local lesion and viable
counts of Freeze-Dried BCG vaccine sealed either in vacuum or in
the presence of nitrogen. For this, half of the ampoules of a batch
of vaccine prepared in Madras BCG Vaccine Laboratory were sealed
in vacuum and the other in presence of nitrogen. Randomly
selected ampoules of both types of vaccine were exposed to 37o and
44o for 2, 6, and 18 weeks and another set at 4oC for 18 weeks.
Two batches of liquid BCG vaccine were made as controls: 16 types
of ampoules thus obtained were randomly repeated 5 times according
to Standard Lattice Design. About 3000 school children without BCG
scar, aged 5-14 years In Bundi and Kota districts of Rajasthan were
vaccinated as per the study design. post-vaccination allergy with
5 TU RT 22 by measuring the size of vaccination lesions was recorded
3 months later. Viable counts on samples of ampoules from Freeze-Dried
BCG vaccines exposed differently were done in the production laboratory
after 18 weeks of storage.
The vaccine in 16 types of ampoules was significantly
different. Liquid BCG vaccine resulted in higher level of allergy
and larger vaccination lesions than Freeze-Dried BCG vaccine sealed
under either method. The study has shown that Freeze-Dried BCG
vaccine sealed under either method vacuum or nitrogen, gave satisfactory
level of post-vaccination allergy and induration size of vaccination
lesions, provided the vaccine was preserved at 4oC. Storage at 37o
for more than 2 weeks and even 2 weeks storage at 44oC affected
both types of vaccine badly as shown by post-vaccination allergy
and viable counts. However, decrease in viable count with time and
temperature was more pronounced in vaccine sealed in presence of
nitrogen. Hence, there is a need to provide cold chain facility
for Freeze-Dried vaccine all throughout the period.
|KEY WORDS: LIQUID BCG, FREEZE-DRIED BCG.