HIV Vaccine Remains Elusive
STEVE INSKEEP, host:
Twenty-five years ago, doctors described the first five cases of a new disease that became known as AIDS. Today, and every day this year, more than 11,000 people will get infected with HIV, the virus that causes AIDS. Nearly 8,000 will die each day.
The world has made progress against AIDS, but experts agree the pandemic will not end until science comes up with an effective vaccine. NPR's Richard Knox explains why that goal remains out of reach.
RICHARD KNOX reporting:
On April 23, 1984, federal health authorities called a press conference to announce that American scientists had discovered the virus that causes AIDS. That's when Margaret Heckler, then the Secretary of Health and Human Services, made a famous prediction.
Ms. MARGARET HECKLER (Former Secretary of Health and Human Services, Reagan Administration): Is one able to develop a vaccine to prevent AIDS in the future? We hope to have such a vaccine ready for testing in approximately two years.
KNOX: An AIDS vaccine by 1986. The politicians weren't the only ones who were overconfident. Dr. Robert Gallo was then the government's star AIDS researcher. In a later interview with the BBC, he admitted he, too, was naïve.
Dr. ROBERT GALLO, M.D. (Director, Institute of Human Virology and Division of Basic Science, University of Maryland Biotechnology Institute): When asked, well, when will you have a vaccine, I thought to myself, well, when? Let's give some estimate. We can grow the virus forever in culture. That's means we can produce tremendous amounts of virus particles. Gee, that means in a few years we should have a vaccine.
KNOX: Well, the world didn't have an AIDS vaccine by 1986 or 1996 or 2006 - not for lack of money. The federal government has spent $3.4 billion to find an AIDS vaccine. The results have been disappointing, to say the least. Here's vaccine researcher Donald Francis three years ago, announcing the results of the first large-scale human experiment on the most advanced AIDS vaccine of the day.
Dr. DONALD FRANCIS (Co-Founder, President, VaxGen): There was no effect of the vaccine whatsoever in preventing HIV infection.
KNOX: Why has it been so hard to make a vaccine against HIV? We asked Dr. Anthony Fauci of the National Institutes of Health. He oversees virtually all the government's AIDS research.
Dr. ANTHONY FAUCI (Director, National Institute of Allergy and Infectious Diseases, National Institutes of Health, U.S. Department of Health and Human Services): The human body does not handle HIV very well. There is not a single documented case of someone who's developed HIV infection where the immune system has spontaneously, truly eradicated the virus from the body.
KNOX: Fauci says traditional vaccines don't provide any recipe for a vaccine against HIV.
Dr. FAUCI: Most vaccines against microbes, even the microbes that are the big killers - smallpox, measles, polio, et cetera - mimic natural infection.
KNOX: Natural infection with one of these germs generates a life-long arsenal of antibodies. They block repeat infection. A shot of vaccine against smallpox, measles or polio does the same thing without causing the disease.
Dr. FAUCI: Unfortunately, we don't have that with HIV. The body has already showed us that it is not capable of making a good protective response against HIV.
KNOX: Scientists call it the antibody problem. HIV coats itself with sugars that make it virtually invisible to antibodies. On top of that, it constantly changes its outside coating. That's why Don Francis's vaccine didn't work in 2003. People who got it made antibodies, but it was like firing blanks at the enemy.
So AIDS vaccine researchers have moved away from vaccines that focus on generating antibodies, at least for now. But there are plenty of new vaccine approaches in the works.
Ms. Christine MCGRIGAN(ph) (Nurse, Brigham & Women's Hospital, Boston, Massachusetts): How are you doing today?
KNOX: One of them is at Brigham and Women's Hospital in Boston, called HVTN 204. Nurse Christine McGrigan is about to use a special vaccine gun to shoot an experimental AIDS vaccine, or maybe just a dose of placebo, into the left arm of a 32-year-old woman named Denise(ph).
Ms. CHRISTINE MCGRIGAN: (Unintelligible) your arm.
Ms. MCGRIGAN: Okay.
Ms. MCGRIGAN: Do you like to know?
DENISE: Just do it.
Ms. MCGRIGAN: Sorry.
(Soundbite of vaccine gun)
DENISE: Oh, that's not bad.
Ms. MCGRIGAN: I've perfected my technique.
KNOX: Denise doesn't want her full name on the radio because she's afraid others will assume she's infected with HIV. She isn't, but the virus has come very close to her; that's why she volunteered for the experiment.
DENISE: It goes a little bit deeper for me, personally, as to why I'm doing it, because it hits home. My mother died of AIDS and my brother - he's an adult now - he made it past, you know, his life expectancy, so I'm very happy about that, but he still carries the virus. So whatever I can do to help, I'm willing to do that.
KNOX: Denise is one of 19,000 people around the world enrolled in at least two-dozen AIDS vaccine trials. Most of these studies use vaccines to stimulate another arm of the immune system called cellular immunity. That's different from antibody immunity. Fauci of the NIH explains that cellular immunity generates blood cells that recognize infected cells and kills them.
Dr. FAUCI: That's the kind of vaccine that might blunt or inhibit the progression of disease, but has little chance of actually preventing the infection.
KNOX: Little chance of preventing the infection. In other words, the first generation AIDS vaccines won't protect most vaccinated people from getting HIV. How much protection will they provide?
Dr. FAUCI: Ah, you can't say precisely what it is. The number that's kicked around most frequently is around 30 percent.
KNOX: So 70 percent or so will still be at risk of getting infected after getting a shot of that first generation vaccine. But if they do, researchers hope they'll be less likely to get sick or pass the virus to someone else. Fauci acknowledges those first vaccines will be a hard sell.
Dr. FAUCI: That is clearly a difficult thing to get across to people, because people just generally don't hear that; they think vaccine, they think protection. So you've got to make it very, very clear that, even at its best, the vaccine might not necessarily, and likely will not necessarily, protect you against infection.
KNOX: Other problems confront vaccine researchers. One of the biggest is that HIV is a diverse and constantly changing family of viruses. That's raised the fear that it might take a different vaccine for each sub-type, and that those vaccines would quickly become obsolete as the viruses mutate.
Not necessarily, says Dr. Bruce Walker, of Massachusetts General Hospital.
Dr. BRUCE WALKER (Director, Partners AIDS Research Center, Division of Infectious Diseases, Massachusetts General Hospital): One of the things that we now realize that we didn't a few years ago, is that HIV is actually much more predictable than we ever thought it was.
KNOX: The virus prefers to mutate in certain ways, and avoids others. Walker says that opens up the possibility that researchers might make a vaccine that can anticipate HIV's mutations and block their escape routes.
Dr. WALKER: A vaccine that not only protects against what HIV is, but what HIV will predictably try and become when the immune system starts to attack it.
KNOX: Fauci says that may be possible, but not tomorrow.
Dr. FAUCI: Before we get to that, we've really got some baby steps to take first about getting any immune response that is adequate to protect.
KNOX: How long will that take? Fauci won't guess. Maybe he's thinking of Bob Gallo's 1984 forecast. Too many people have gone up in smoke, he says, when they've tried to predict when we'll have an AIDS vaccine.
Richard Knox, NPR News.