LIVE POLIO IRUS VACCINES

Virological Findings, Antibody Response of Infants Fed Multiple, Oral Vaccine 275
additional infants from whose pre-feeding stool
specimens an enterovirus was isolated but was
not identifiable with the immune sera on hand.
Here the picture is somewhat different; only
child No. 30 showed consecutive isolations of
Types 1 and 3 poliovirus with a corresponding
serological response. Two infants, Nos. 19 and
126 responded to a single type only. Four children
did not excrete any of the vaccine viruses
nor did they show any antibody response in their
post-feeding sera. An unidentified virus isolated
in the pre-feeding specimen from infant No.
71 was again isolated from two post-feeding stool
specimens.
COMMENT
Several points emerge from these findings. It
has been shown that infants three to four months
old, readily excrete the poliovirus strains fed for
a period of at least four weeks. Only 6 per cent
of the infants fed did not excrete any of the poliovirus
types fed. These findings compare favorably
with results obtained in older children. 8 1
-
Results of the virological findings, together with
the corresponding homologous serological responses,
indicate by the percentage of positives,
as well as the high antibody titers, that infants
three to four months of age may be effectively
immunized with a multiple type oral poliomyelitis
vaccine. It is regretted that no adequate
information has been obtained with regard to the
Type 2 poliovirus. Although the Lederle Type
2 strain has been previously reported to be poorly
excreted," 12 the almost total absence of this
strain in the post-feeding stool specimens of infants
fed the oral vaccine and the corresponding
negative antibody response may be assumed to be
due to the low concentration of this poliovirus
type in the trivalent vaccine used for feeding.
A very high correlation between poliovirus
types isolated and the corresponding antibody
response has been demonstrated, indicating that
the techniques used for virus isolations and
identifications were satisfactory. In approximately
70 per cent of the infants studied, two
types of the vaccine polioviruses multiplied adequately
as judged by virus isolations and the
immunological response. In a small per cent
only a single type multiplied; this may be due to
either interference between the poliovirus types `
or to factors associated with individual responses.
Presence or absence of maternal antibodies did
not seem to affect virus excretion or homotypic
antibody response although there were too few
children with high antibody levels to draw definite
conclusions. The studies on the children excreting
enteroviruses other than polioviruses
demonstrate that the problem of interference is
not as serious as previously reported. Of the 14
infants observed, 10 showed multiplication of at
least one, and mostly of both poliovirus types fed,
sometimes in combination with the pre-feeding
enteroviruses. Lack of interference in the
majority of the infants may be the result of the
high dose of the multiple type oral vaccine administered,
as previously suggested by Cox
et al.l 2
and by Sabin.`T
REFERENCES
1. Yekutiel, P., Levinger, E. L., Muhsam, H. V..
and Yekutiel, M. P.: Poliomyelitis outbreak
in Israel, 1950-1951. Bull. World Health
Org. 12: 651-676, 1955.
2. Davies, M. A., Marberg, K., Goldblum, N.,
Levine, S., and Yekutiel, P.: Epidemiology of
poliomyelitis in Israel, 1952-1959 with evaluation
of Salk vaccination during a three-year
period. Bull. World Health Org. In press.
3. Spigland, I. and Goldblum, N.: Immunization
of infants with formalinized poliomyelitis
vaccine. Pediatrics. In press.
4. Koprowski, H., Norton, T. W., Hummeler, K.,
Stokes, Jr., J., Hunt, A. D., Flack, A., and
Jervis, G. A.: Immunization of infants with
living attenuated poliomyelitis virus. J. Am.
M. Assn. 162: 1281-1288, 1956.
5. Martins da Silva, M., McKelvey, J. L., Prem,
K. A., Bauer, H., Cooney, M. K., and Johnson,
E. A.: Studies of orally administered
attenuated live virus poliomyelitis vaccine
in newborns and infants under six months.
Univ. Minn. M. Bull. 29: 133-150, 1957.
6. Plotkin, S. A., Koprowski, H., and Stokes, J.:
Clinical trials in infants of orally administered
attenuated poliomyelitis viruses.
Pediatrics 23: 1041-1062, 1959.
7. Prem, K. A., McKelvey, J. L., and Fergus, J.:
Immunologic response of infants under six
months of age to oral trivalent poliomyelitis
vaccine. In: Live Poliovirus Vaccines, First
International Conference. Scient. Pub. no.