AEGiS-AIDSWeekly: Conference Coverage: UNAIDS Descries "AIDS Exceptionalism" -

Important note: Information in this article was accurate in April 1999. The state of the art may have changed since the publication date.

Conference Coverage: UNAIDS Descries "AIDS Exceptionalism"

AIDSWEEKLY Plus; Monday, April 19, 1999
Daniel J. DeNoon, Senior Editor

CW HENDERSON PUBLISHER -- Is AIDS the exception to established norms of vaccine-development?

No, says Jose Esparza of the Joint United Nations Program on HIV/AIDS (UNAIDS). He suggested that the development of an HIV vaccine is "paralyzed" by issues that have been solved for other vaccines.

"Everything is magnified under the microscope of AIDS," Esparza said in a presentation to the Second Annual Conference on Vaccine Research, held March 28-30, 1999, in Bethesda, Maryland.

The UNAIDS representative listed a number of perceived obstacles to an AIDS vaccine:

The genetic variability of HIV makes a vaccine exceptionally difficult. Esparza pointed out that genetic variability is not unique to HIV, and that clade C HIV-1 is responsible for some 50 percent of infections.
The predictive value of primate models is unknown. Esparza suggested that this concern only increases the relevance of performing human trials as soon as possible.
The quantity and quality of the immune responses needed to control HIV are unknown. Esparza noted that the correlates of immunity remain unknown even in diseases for which effective vaccines are available.
The debate over the scientific versus the empiric approach to AIDS vaccine development. Esparza called this distinction a "fallacy." "We have to have a balance of these," he said.

Borrowing a slide from the late Mary Lou Clements-Mann's presentation of a year ago, Esparza listed a number of misconceptions about an HIV vaccine:

It must prevent infection.
It must prevent all disease.
Immune responses elicited by a vaccine must be those seen in natural infection.
Vaccines always induce life-long immune responses.
Protective efficacy must be demonstrated in animal models before human efficacy trials can begin.
Correlates of protective immunity must be known before efficacy trials can begin.
Only one efficacy trial will be needed.
Trials that fail to demonstrate efficacy will set back research.

These misconceptions, Esparza said, must be replaced by an iterative process between basic science and clinical trials. He endorsed Clements-Mann's proposal for the simultaneous development of many HIV vaccine concepts in many clinical trials and multiple international sites.

With regard to this latter point, Esparza called on nations facing existing AIDS crises to join the battle.

"Help must come from the South," he said. "The epidemic is very bad in India and in South Africa. ... These are countries that feel the urgency of the need for an AIDS vaccine and have the infrastructure to help develop vaccines."

He noted that in every nation that has prepared for AIDS vaccine trials there has been a similar public response:

Initial opposition. Esparza called this the "Guinea-pig phase," in which the host nation sees itself as being used for trials developed nations are unwilling to perform themselves.
Support and normalization. With international public relations support - e.g., World Health Organization (WHO) delegations and lobbying by local non-governmental organizations - there is a rising tide of support for vaccine trials.
Frank support. At this stage, local government and doctors participate.
Consensus building. This involves a national project to discuss the vaccine trial protocol and to establish guidelines.
Preparation for trials. This stage must include immediate assurances of future availability of any product developed as a result of the trials, Esparza said.

Ray Spier, editor of the journal Vaccine, noted in a comment from the floor that it is important in each nation to discuss the conditions that will prevail for vaccine trial participants who become infected with HIV.

"That is where there is a lack of consensus," Esparza said. "I think wherever you conduct a trial, you should provide the best care available in the world. Others say just use the prevalent standard of care. But I do not believe this - too often the prevalent standard of care is too low."

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