Issue Number 1001 | Eulogy for a Doomed Vaccine | Advocate.com Eulogy for a Doomed Vaccine  |  | Advocate.com

Advocate.com health Channel
||  Health  ||
 
Eulogy for a Doomed Vaccine
What happens when an HIV vaccine not only fails to prevent infection but may actually help cause it? Sean Kennedy assesses the second major vaccine study to go belly-up -- and his own participation in it.
From The Advocate  January 29, 2008
Eulogy for a Doomed Vaccine

 It was bad enough when a promising HIV vaccine’s global trial was halted last September because the drug under study failed to prevent infection. But it got even worse when scientists discovered in November that in some of its recipients the vaccine might actually have promoted HIV infection. The twist was like a sick joke: A product designed to protect people from HIV could instead help them get it?

The vaccine under study -- only the second ever to garner a critical Phase II clinical trial -- was expected to be a major breakthrough in the fight against HIV. Developed over the course of a decade by drug company heavyweight Merck & Co. and being tested in nearly 3,000 people from North and South America, the Caribbean, and Australia, the vaccine was designed to stimulate the body’s T cells in order to better ward off the insatiable virus. The previous vaccine to reach the Phase II stage had targeted antibodies, the immune system’s other set of defenders, but it had proved a bust in 2003. Hopes were high that the T-cell approach would succeed.

Instead, a midpoint analysis made public on September 21 showed statistically comparable rates of infection for volunteers (all HIV-negative at the start of the trial) who had received the vaccine and those in the placebo group. What’s more, in those vaccine recipients who became infected with HIV, the vaccine also failed to lower their virus levels -- another area of inquiry for investigators. The vaccine was a loser, and there was nothing to do but stop the three-year-old trial.

It was a devastating denouement for anyone aware of the stakes—experts widely believe that a vaccine, if not a cure, is the only thing that can turn around the runaway HIV/AIDS pandemic. But like a thriller, this trial held one last plot surprise in store: People who had received the vaccine were in fact becoming infected with HIV at a higher rate than those in the placebo group. According to the latest data available, 49 of the 914 men who received the vaccine became infected with the virus, while 33 of the 922 who received the placebo tested positive. (The remaining 839 volunteers were women, only one of whom became infected.)

Suddenly what had been a straightforward story of loss became a vexing mystery. Although the vaccine was made with three HIV genes, they were synthetic -- like Xerox copies of original documents -- so it was impossible to get infected from the vaccine itself. That left two possible explanations: Either vaccine recipients who contracted the virus guessed that they had been vaccinated -- like any legitimate scientific study, the trial was double-blind, meaning neither subjects nor researchers knew who received what—and, assuming they were protected, consequently engaged in riskier behavior. Or, more probably, the vaccine facilitated infection in some way.

Indeed, the leading hypothesis among investigators is that the vaccine somehow made the immune system more susceptible to infection. However, the increased susceptibility appears to be limited only to those vaccine recipients who had a pre-existing immunity to the cold virus used in the vaccine to transport the HIV genes into the body. For reasons that still need to be determined, that was the group that saw an increase in HIV infection. If you had been given the vaccine but had lower immunity to the cold virus, your risk was likely no greater than that of the placebo recipients.

Page: 1 | 2 | 3

Reader Comments

These comments are reproduced as written by visitors to this Web site. They have not been edited for content, grammar, or spelling. The viewpoints appearing here are those of the writer, and do not necessarily reflect the opinion or views of advocate.com, The Advocate, or its affiliates.

Be the first to comment on this story.

Back to top

Submit a comment for this story:

*Type your comment here (Required, 1000 characters max.):

*Name (Required): 

*Hometown (Required): 

*E-mail address: (Required, but will not be displayed)

Is this comment for publication? 
Yes   No

Daytime phone number: (Required for print publication only and will not be displayed)

Please enter the words you see in the box, in order and separated by a space. Doing so helps prevent automated programs from abusing this service.

  

If you would like to submit a comment for posting, please fill out the form above. 

All comments submitted via this form are subject to posting or publication. (To send a private letter to an Advocate editor or writer, please use the e-mail button at the top of the page, or use snail mail.) If you would like your comment considered for publication in The Advocate magazine, please include your full name, your city of residence, and a phone number where you can be reached during business hours so that we can confirm your identity. Your e-mail address and telephone number are strictly confidential and will not be shared or used for any purpose other than to contact you about your comment.

Comments that do not concern specific articles in The Advocate or on Advocate.com will not be posted or published. See the Contact page for sending comments for reasons other than responding to Advocate editorial and news stories.

Please note that comments sent by fax or snail mail are unlikely to be posted, although they will be considered for publication along with all letters received via e-mail or via this Web page. Comments that chiefly concern Advocate.com content will be considered for posting only on the Web site. The Advocate reserves the right to edit submitted comments for grammar, spelling, obscenities, or libel; we will, however, do our best to preserve the original comment's style and intent. Comments considered for publication in The Advocate magazine may also be edited for length.