IAVI Report Vo. 5, no. 2

Wide Range of Issues Discussed at the
3rd Conference on Vaccine Research
by Pat Fast

The Third Annual Conference on Vaccine Research, held on
30 April-2 May 2000 in Washington DC, included data on a
broad range of vaccine-related topics from polio eradication to
pre-clinical studies of new vaccines in development.
A number of presentations addressed different ways to
deliver vaccines including by intranasal, oral, intradermal
(applying it to the skin) administration or using a "jet injector".
Needle-less injections have great practical advantages,
particularly in terms of mass immunizations. The best example
is the current polio eradication campaign, which utilizes the
oral polio vaccine. (2000 is the target year for eradicating this
disease.) The vaccination of 147 million people in India in
one day is an extraordinary example of the power of a true
national commitment to disease eradication.
On a more sobering note, a resurgence of measles, which
was seen recently in Latin America, is an example of how the
failure of even one relatively small group to fully commit to
disease eradication can put an entire continent at risk.
The conference opened with two talks on the economics of
vaccine development and
distribution. Amie Batson, of the
World Bank's Human Development A number ofpar
Network, described efforts of the
HIV "vaccinolo3
World Bank, UNAIDS, the Bill and
Melinda Gates Foundation, IAVI and become more i
others to develop "Push" and "Pull"
mechanisms to stimulate HIV vaccine larger world ofJ
development. ("Push" mechanisms developmen
include funding or creating
incentives for research and
development, while "Pull" mechanisms, which include vaccine
purchase funds, are designed to create a market for vaccines
once they are developed.)
Batson pointed out that as long as many existing vaccines
are not purchased and distributed globally, it will be difficult,
if not impossible, to convince vaccine manufacturers that an
HIV vaccine can be distributed worldwide. For example, the
H. influenzae type B (HiB) and Hepatitis B vaccines are highly
effective against diseases that kill large numbers of children
and adults, yet they are unavailable to much of the world.
Michel De Wilde of Aventis Pasteur described the significant
investment vaccine manufacturers incur at different stages of
development. Research and development costs can now reach
into the tens of millions of dollars for pre-clinical work and
total more than US$300 million after manufacturing scale-up
and registration with regulatory authorities. In the view of
many at the conference, the costs of licensing vaccines have
been largely underestimated.
De Wilde described a typical dilemma within a company:
the decision to initiate efficacy trials and commit to the long
and expensive process of scale-up hinges on scientific
feasibility as well as economic concerns. Ideally, the decision

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to scale up manufacturing will be taken long before efficacy
results are available, since scale-up and testing can take several
years. Unfortunately, unlike a therapeutic agent, it is very
difficult to have a high degree of certainty about preventive
efficacy without data from a Phase III trial.
Encouragingly, however, a number of participants noted
that HIV "vaccinology" is beginning to become more
integrated into the larger world of vaccine research,
development and delivery. It is now recognized that progress
in overall vaccine development and distribution will
undoubtedly help move HIV vaccine development forward,
and vice-versa.
Many of the presentations also reflected the need to
produce cheap, easily delivered vaccines. These included
reports on "edible" vaccines, other simplified delivery systems
and new adjuvants that may reduce the dosage or required
number of immunizations. The Seattle-based Program for
Applied Technology in Health (PATH) presented a plan for
making vaccines with improved
thermostability available for the
developing world.
ipants noted that Francine McCutchan of the Henry
is beginning to M. Jackson Foundation presented
is beginning to
interesting data on the molecular
grated into the epidemiology of HIV epidemics.
ccine research, Using serological methods, Phil
ccine research, Renzullo of the U.S. Walter Reed
'nd delivery. Army Research Institute of Research
(WRAIR) and colleagues
demonstrated substantial diversity of
HIV strains in infected applicants for U.S. military service.
Antibodies preferentially binding V3 loops from A or C, D, or F
strains were found in about 2% of applicants and a variant of B
that predominates in Brazil was found in another 5%. These
atypical B V3 serotypes in the military applicants included a
variety of patterns, including B/D, B/F and others, in addition
to the "Brazil B" peptide. Researchers also described new
recombinant HIV strains in Thailand and China. Interestingly,
McCutchan also reported that the progression of HIV diversity
was less when HIV was transmitted intravenously through drug
use than in a cohort where sexual transmission predominated.
A few preclinical studies of HIV vaccine candidates were
presented. The most striking was a late-breaker presentation
by researchers at the University of Rochester, the University of
Cape Town and MedImmune Corp. Virus-like particles of a
strain of human papilloma virus (HPV) associated with cervical
cancer were found to be immunogenic when given orally to
mice. The virus-like particles can also be modified to act as
carriers for other antigens such as HIV.
Data on a number of adjuvant and antigen-presentating
strategies were also discussed. Heather Davis of the University
of Ottawa presented evidence that in a Phase I hepatitis B trial,
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