San Francisco Chronicle - September 13, 2004

Given this worldwide threat, why can't scientists produce a magic-bullet vaccine? Smallpox, polio, measles and yellow fever are largely eradicated, thanks to drugs that prevent infection. Why haven't medical research, political pressure and government support produced a preventive for AIDS?

There is no simple answer. But asking the question has provoked a debate in the AIDS world about how best to spend scarce dollars and resources on a runaway epidemic.

To scientists, AIDS is the virus from hell. It constantly mutates, slipping away from a basic blueprint needed by vaccine designers. Researchers have tried numerous approaches, first tapping antibodies that make up other vaccines and then trying to rev up the body's cellular system.

There are 22 candidate vaccines now in human trials, but none promises a huge breakthrough. One recent drug trial in Kenya is typical: After six years of work, a promising vaccine was effective in only 20 percent of the cases. Unless the numbers improve in further tests, its backers may dump the trial.

These results, along with similar flops in earlier studies, have made AIDS vaccines controversial. There are the optimists, such as the International AIDS Vaccine Initiative, who are sold on the need for more research. With a dose of realism, they believe research will cost more than $1 billion and take at least a decade. Their mantra is that without a vaccine, there can be no hope. Prevention programs, drugs to subdue symptoms and vast social-service programs aren't enough, these advocates say.

Others aren't sold on this view. Let research continue, but don't allow the prevention and treatment budgets to suffer for a long-shot vaccine cure. Without substantial tax breaks or government subsidies, big drug companies won't commit to the expensive and lengthy research. And imagine if a magic bullet was found. What would the price be and who would control it? At an AIDS conference in Bangkok in July, vaccines elicited little attention because the reality is so distant.

There is a middle ground that needs defending. A vaccine should be designed, but its limits recognized. Though familiar vaccines generally offer total protection from an invading disease, it's likely that an AIDS answer won't come with an ironclad guarantee. Researchers expect an AIDS vaccine would reduce, not eliminate, the likelihood of infection.

This humbler version of a vaccine will act by killing the spread of AIDS after the virus has taken up residence -- not ridding the body completely. Medicine's amazing abilities to cure and repair have led the world to expect too much, especially in the case of AIDS.

From the early 1980s, when AIDS was first identified, it has baffled researchers. It's foolish to expect miracles, though partial steps to box it in are possible.

The evolving AIDS virus should encourage public-health planning to be equally adaptable. A vaccine is worth wishing for, but it's not the only choice.

There are other options in the AIDS fight: Microbicides, a germ-killing foam or gel used by women, can cut down risk encountered during sex. More studies are needed to test the potential of this approach.

There is also the "ABC" plan: abstaining from sex, being faithful to limit virus-carrying partners and using condoms. This proposal, referred to as a "social vaccine,'' is ridiculed for its unrealistic emphasis on chastity. Also, women, who are more vulnerable to infection, can't always demand male partners use a protective condom. But the ABC plan is low-cost and has the support of both the Bush administration and the leaders of some African nations.

Other ideas being tested include use of cheap medicine to curb genital herpes, a skin condition that spreads AIDS, and male circumcision, which may lessen infection.

A vaccine, if it can be found soon and put into wide use, would save the planet from a plague that may kill 70 million by 2020. But the world can't wait for a medical miracle. Finding other ways to control AIDS will have to continue.

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