LIVE POLIO IRUS VACCINES

dence of immunization within a few months, but
also a very high interference with dissemination
of polioviruses.
For the present, these are my guiding principles
about the use of monovalent vaccine in some
parts of the world and trivalent vaccine in other
parts of the world.
Discussion 597
Discussion 597
upon the effect of the very highly virulent virus.
Because the past history of provocation has
shown that, when it has been observed, it has
been observed during particularly severe epidemics;
during the course of ordinary dissemination
it has not.
Now, with the Type 1 virus which we are administering,
and with the evidence of the complete
absence of viremia, which has now been
confirmed by the excellent studies of the Czech
investigators on triple-negative children of this
particular age group of three to six months, I
believe the question of provocation is a very
minor one-and perhaps actually nonexistent.
Furthermore, in Cincinnati, the only thing that
we stopped, in order to avoid any possible problems
coming up, were tonsillectomies and ade-
DR. ToBIN: There is one thing that worries me
just a little about Dr. Sabin's suggestion that live
vaccine should be given in the three-to-six-month
age group. This is that at that time many infants
will be receiving triple vaccine (diphtheriatetanus-pertussis),
which may have a certain
amount of provoking effect.
I was wondering if Dr. Sabin thinks there is
any danger of poliomyelitis provocation with
triple vaccine in children vaccinated with his noidectomies.
attenuated strains. However, on immunological
grounds, I should have thought that giving live
vaccine is better at that age than giving the
killed one.
Because data on antibody responses in infants,
presented during this meeting, seem to indicate
that these responses persist for at least a year,
I would disagree with Dr. Gard. I should have
thought that in the case he mentioned and after
live vaccine has been fed to infants, one would
give killed vaccine to boost the antibody response.
We have found that there is no difference in the
fall of Types 1, 2, and 3 after a third dose, as
long as this gives a true secondary response.
This depends on people having circulating antibody
at the time of this dose.
DR. SABIN: If I understood Dr. Tobin correctly,
he suggested the possibility that, in a
child who has had killed virus vaccine, Salk vaccine-is
that right?-or any kind of vaccine,
administration of live virus vaccine may involve
a provoking effect.
DR. TOBIN: No.
DR. SABIN: The triple vaccine you refer to is
diphtheria, pertussis, and tetanus?
DR. TOBIN: Yes, you are giving the triple vaccine
simultaneously, you see.
DR. SABIN: I should say that whatever the
mechanism of provocation may be, it depends
For the present, we did not want
to be involved with this particular problem.
But, otherwise, all other vaccinations have gone
on during the period of administration of the
oral vaccine to these very small babies and, as I
have mentioned, six weeks have gone by and we
have had absolutely no problems whatever.
DR. LANGMUIR: As an old hand at the eradication
business, and one whose hands have been
burned, 1 should like to welcome Dr. Sabin to this
fold.
I had hoped earlier that the Salk vaccine would
have influenced the spread of virus sufficiently to
make this threshold of immunization a realistic
one. But, with the data from many people in this
room and Dr. John Fox not here, is was obvious
that there was a difference, or a far greater continuity
of virus in stool after Salk vaccination
than 1 had anticipated.
I should like to say, however, that the epidemiological
evidence in this country seems to me
to be pointing rather strongly to the conclusion
that there is an effect on spread of virus by Salk
vaccine. Essentially, the pattern of concentration
of cases in these unvaccinated areas and the absence
of infection within large areas of upperclass
communities impress me as evidence of the
influence of Salk vaccine on spread.
It seems to me that if Dr. Sabin is to succeed in
his objective in Cincinnati he has some very real
problems that are going to continue for some
time. He must have a very thorough coverage of
the newborn infants in the community to a very