LIVE POLIO IRUS VACCINES

Live Virus Vaccine Studies in Southern Africa
475
TRIALS CONSIDERED
In the immunity survey of the population of
the island of Tristan da Cunha, which is a lonely
island halfway between Buenos Aires and Cape
Town, in 1955, of the 70 individuals tested, varying
in age from two to 45 years, most of them
had antibodies to Type 3 virus, but only one had
antibody to Type 1 virus. I believe that most of
the antibodies to Type 2, about 23 per cent, are
due to heterotypic antibody developed as a result
of this wave of infection. As poliomyelitis due to
Type 1 poliovirus was then prevalent in Cape
Town, the port from which ships sailed to supply
the island, it was considered advisable to protect
the population against this infection and it was
suggested that they should be immunized by
feeding with Dr. Koprowski's SM and TN strains.
Dr. Koprowski arrived in South Africa and was
available for consultation shortly after this. The
suggestion was approved by the medical authoritiíes
of the British Colonial Office and the British
Medical Research Council, but for various
reasons, it was not considered to be expedient
by higher authorities and it was not carried out.
Early in 1956, the beginning of an epidemic in
an African native township in East London was
brought to our notice by Dr. Sinclair-Smith, the
Medical Officer of Health of that city. The epidemic
was proved to be due to a Type 1 virus,
and the possibility of feeding an attenuated Type
1 strain in the face of this epidemic was discussed
and a supply actually flown to East London. However,
on further consideration, it was again
decided not to administer the virus. The epidemic
continued and developed into the worst
and most severe experienced in such a township.
RECENT STUDIES
In 1957, the Advisory Committee on Virus
Diseases of the Union Health Department agreed
that trial feedings of attenuated virus could be
carried out in the face of an impending epidemic,
preferably when it occurred in a relatively isolated
community. No such circumstances have
since developed in the Union of South Africa,
in which formalinized vaccine has been used on a
relatively large scale.
Mauritius. In July 1959, the Director of
Medical Services of the Island of Mauritius in the
Indian Ocean, notified us of a sharp epidemic
then developing in the island. It was suggested
to him that an attempt should be made to bring
the epidemic to an end by feeding attenuated
virus of the same type as that causing the
epidemic.
Specimens from 10 cases were flown to the
Poliomyelitis Research Foundation and the virus
identified as a Type 1 strain.
Dr. P. D. Winter, Head of the Vaccine Division
of the Poliomyelitis Research Foundation,
then flew to Mauritius, taking with him 250,000
doses of Sabin's LSc Type 1 strain, prepared in
the laboratories of the Poliomyelitis Research
Foundation, and tested for safety according to
our own criteria.
An immunity survey of the population had been
carried out in 1955. The results of the tests on
80 children under 10 years old are shown in
Table 1.
In September 1957 Salk type vaccine was
offered to all children between one and five years
old, in September 1958 to all between the ages of
one to two years, and in April 1959 to all between
one and two years. By the end of June
1959, the vaccination status of the children between
one to seven years old was:
3 doses vaccine
2 doses vaccine
1 dose vaccine
0 dose vaccine
43,395
35,603
46,120
25,790
TABLE 1. POLIOMYELITIS IMMUNITY-MAURITIUS-1955
ANTIBODIES
AGE GRouP
1-5 years
6-10 years
TOTAL
+
37 21
43 35
TYPE 1
16
8
23
38
TYPE 2
+
14 27
5 29
TYPE 3
10
14