LIVE POLIO IRUS VACCINES

184
Safety-Field Evidence of Safety
cine, was designed for an epiderniological study.
Such results do not have direct bearing on other
programs of different design calculated to immunize
a whole population against poliomyelitis,
particularly by mass administration of the vaccine
such as the program in progress in the same
general area as our study. We do not as yet have
data from this larger program, but are particularly
grateful to the local health authorities of Costa
Rica for the privilege of carrying out this trial in
an area where considerable experience had been
gained with regard to live poliovirus vaccination.
CONCLUSIONS
Emphasis has been placed in this small study
of 48 families living in a subtropical environment,
on what can be learned from the standpoint of
human experimental epidemiology of poliomyelitis.
Major aims have been to determine the
capacity to infect on the part of the Lederle
strains of attenuated poliovirus when given in the
form of a trivalent vaccine in two doses one month
apart. Particularly have we tried to determine
the reasons which can be ascribed for the failure
of some strains to "take." We have also studied
the pattern of intrafamilial spread of these infections.
It is to be emphasized that the conclusions
reached apply only to one small study carried on
within a special framework.
ACKNOWLEDGMENTS
Grateful acknowledgment is expressed by the
authors to the following: Dr. José Manuel
Quirce, Minister of Health, and Dr. Oscar Vargas-Méndez,
Director General of Health, Costa
Rica; Dr. Juan A. Montoya, Pan American Sanitary
Bureau Epidemiology Consultant, and Dr.
Joaquín Núñez, Technical Director, National
Campaign against Poliomyelitis, Costa Rica; also
to Mrs. María José Ramírez Vargas, and Miss
Jael Chacón Zamora, Santo Domingo de Heredia
Health Center, Costa Rica. Without the cooperation
of these individuals this study would not have
been possible.
REFERENCES
1. Horstmann, D. M., Paul, J. R., Isacson, E. P.,
and Niederman, J. C.: Effectiveness of trivalent
vaccine in immunizing young children.
Studies on the stability of the vaccine strains
after human passage. (See this volume, pp.
113-120).
2. Webster, L. T.: Experimental epidemiology.
Medicine, Balt. 25: 77-109, 1946.
3. Paul, J. R.: The epidemiology of poliomyelitis.
Delivered at a Symposium on Infantile
Paralysis, Vanderbilt University, April 1941.
Balto., The Waverly Press, 1941.