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14
The kidneys are placed in large bottles, minced and
covered with a fluid that will support the growth of the
kidney tissue. They are then kept at body temperature for
a few days. The virus is now added to the bottles and they
are returned to the incubator. At the end of three days,
by which time all the kidney cells have been killed and
the multiplication of the virus units has ceased, the fluid
in the bottle contains enormous numbers of virus particles.
Each virus particle has given rise to 10,000 more particles.
The number of particles in the dose of vaccine required
to protect one child against poliomyelitis is 30 million.
The virus fluid is now removed from the bottles and
the living virus killed by adding formalin.
The final vaccine is a mixture of three vaccines made
separately from each of the three types of poliomyelitis
known to science.
Tests of the vaccine are made at all stages of production
by the manufacturers and the final vaccine is tested
both by the manufacturer and also by the Department of
Biological Standards.
As a final safeguard against a dangerous vaccine, a
sample of each batch is injected into some fairly healthy
monkeys. After four weeks observation the monkeys are
killed and the brain and spinal cord of each removed and
prepared for examination under the microscope. In this way
it is possible to detect infection with poliomyelitis even
though it is not sufficiently severe to have caused paralysis.
A still further degree of safety is thus assured.
PUERPERAL PYREXIA.
43 notifications were received, 44 from Perivale
Maternity Hospital and 4 from private practitioners, which
is 10 fewer than in the previous year.
The value of these figures for statistical purposes
is unreliable. It will be remembered that any febrile condition
in which the temperature reaches 100.4°F on any
one occasion within 14 days of childbirth or miscarriage
must now be notified. The detection of such a temperature
in maternity hospitals is rendered possible, but even here
by no means certain, by the hospital routine of recording
four hourly thermometer readings but many cases which
would qualify for notification must be missed in home