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| Quality Control in Vaccine Production |
Quality Control in Vaccine Production
Quality control of vaccines is done to
provide assurance of both the efficacy and the safety of every batch of
vaccines.
Quality
control of vaccines is performed in three stages:
1. In-process control
2. Final product control
3. A step to determine the consistency of
starting materials, intermediates, final products and the processing methods.
In-process
control:
It is the process in which the control is
exercised over starting materials and
intermediates.
Examples
of In-process control:
1. The quality
control of both diphtheria and tetanus vaccine requires that the products are
tested for the presence of toxin.
The specific toxicity is caused by improper
detoxification with formalin at the final product stage.
The toxoid concentrates used in the
preparation of vaccines are diluted because the volume of the vaccines to be
inoculated into animals is limited. The
tests are relatively insensitive.
In-process control increases the sensitivity
of the method 100 fold.
2. Adequate
infectivity of the virus from the tissue cultures is an indicator of the
adequate virus content of the starting materials and since infectivity is
destroyed in the inactivation process,
there is no possibility of doing such an estimation after formolization.
3. The
examination of tissue cultures to exclude contamination with infectious agents
from the animal source to detect cells with abnormal features.
For example,
monkey kidney cell cultures are tested for simian Herpes B virus, simian
virus 40, mycoplasma and tubercle bacilli.
Cultures of human diploid cells or continuous
line cells are subjected to karylogical examination or microscopic examination
of chromosomes to ensure that the cells are not changed to impair the quality
of a vaccine or lead to undesirable side-effects.
Final
product control:
It is done to estimate the potency of a
vaccine used in a required dose.
a)Sterility:
Vaccines are required to be sterile. The
preferable method for sterility testing is membrane filtration because it
permits the testing for large volumes without dilution of the test media.
The test system must be able to detect
aerobic and anaerobic organisms and fungi.
The exception of the requirement of sterility
are smallpox vaccine made from the dermis of animals and bacterial vaccines
such as BCG, Typhoid 21A and Tularemia vaccines which contain live attenuated
microorganisms.
b) Freedom
from abnormal toxicity:
The test is simple and its purpose is to
exclude the presence in a final container of a highly toxic contaminant.
Example.
Five mice of 17-22 g and two guinea pigs if 250-350 are inoculated with
one human dose or 1 ml of the test preparation.
All of them must survive for seven days
without any sign of illness.
c)
Presence of aluminium and calcium:
Some vaccines may contain aluminium hydroxide
or aluminium phosphate as an adjuvant. The amount of aluminium in vaccine is
limited to 1.25 mg per dose.
The amount of calcium in vaccine is limited
to 1.3 mg per dose and it is estimated by flame photometry.
d) Free
formalin:
Inactivation of bacterial toxins with
formalin may lead to the presence of small amounts of free formalin in the
final product.
The concentration of free formalin must not
be greater than 0.02%.
Formalin is estimated by colour development
with acetyl acetone.
e) Phenol
concentration:
Phenol is used as preservative for
vaccine, its concentration must not
exceed 0.25% w/v or in some cases it may be 0.5% w/v.
Phenol is estimated by colour reaction with
amino - phenanzone and hexa - cyano - ferrate.
" Quality Control in Vaccine Production "
Written By
Sadia
Akhtar
Student of
Department of Microbiology
Jagannath
University.
Email-
sadiabd810@yahoo.com
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