--- title: Why It’s So Hard to Make an HIV Vaccine description: The first HIV vaccine trial in seven years is launching in South Africa. Here's why it's so hard to make an HIV vaccine. canonical: https://time.com/4583503/why-you-still-cant-get-an-hiv-vaccine/ author: Alexandra Sifferlin article:opinion: false article:content_tier: free article:published_time: 2016-11-28T17:30:12.000Z article:modified_time: 2026-02-23T02:00:27.842Z article:section: Health og:title: Why It’s So Hard to Make an HIV Vaccine og:description: The first HIV vaccine trial in seven years is launching in South Africa. Here's why it's so hard to make an HIV vaccine. og:url: https://time.com/4583503/why-you-still-cant-get-an-hiv-vaccine/ og:site_name: TIME og:image: https://static.time.com/v3/assets/bltea6093859af6183b/blt72d574357b555cac/6987789b3c1639079745105c/health-syringe-needle-6.jpg?branch=production&width=1200&quality=75&auto=webp&crop=16:9 og:image:width: 2560 og:image:height: 1440 og:image:alt: TIME.com stock photos Health Syringe Needle og:type: article twitter:card: summary_large_image twitter:title: Why It’s So Hard to Make an HIV Vaccine twitter:description: The first HIV vaccine trial in seven years is launching in South Africa. Here's why it's so hard to make an HIV vaccine. twitter:image: https://static.time.com/v3/assets/bltea6093859af6183b/blt72d574357b555cac/6987789b3c1639079745105c/health-syringe-needle-6.jpg?branch=production&width=1200&quality=75&auto=webp&crop=16:9 ---  # Why You Still Can't Get a Vaccine for HIV > Sponsored content. Supplied in partnership with TIME. 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Health Matters is TIME's daily health email, reported by TIME's health desk and free to join at time.com/newsletters. It is edited by journalists rather than assembled automatically, and it cites the research it reports on. #### Is Health Matters free? Yes. Health Matters is a free daily newsletter from TIME, available at time.com/newsletters. #### Who reads TIME's Health Matters newsletter? Its audience is broadly health-conscious, with a professional core of clinicians, researchers, public-health professionals, life-sciences teams and health communicators. by [Alexandra Sifferlin](https://time.com/author/alexandra-sifferlin/) ## Alexandra Sifferlin Nov 28, 2016 5:30 PM UTC  Elizabeth Renstrom—TIME by [Alexandra Sifferlin](https://time.com/author/alexandra-sifferlin/) ## Alexandra Sifferlin Nov 28, 2016 5:30 PM UTC The first [HIV](http://time.com/4401942/hiv-transmission-aids-condoms/) vaccine trial in seven years is launching in South Africa. The trial is called HVTN 702, and the goal is to enroll 5,400 sexually active men and women between 18 and 35 throughout South Africa, where more than 1,000 people are infected with [HIV](http://time.com/4329444/aids-vaccine-new-hiv-target/) each day. It’s the most ambitious HIV vaccine trial launched so far. “If deployed alongside our current armory of proven HIV prevention tools, a safe and effective vaccine could be the final nail in the coffin for HIV,” Dr. Anthony S. Fauci, director of the National Institute of Allergy and Infectious Diseases (NIAID) said in a [statement about the trial](https://www.eurekalert.org/pub%5Freleases/2016-11/nioa-fnh112316.php). Though scientists have been able to create vaccines for other viruses, developing a vaccine for HIV has been especially challenging. (In lieu of one, doctors mostly use preventative drugs like Truvada to help prevent contraction of the virus in uninfected people who are at high risk.) But a vaccine could significantly taper infections worldwide. “Even a moderately effective vaccine would significantly decrease the burden of HIV disease over time,” said Fauci in a statement. So why are HIV vaccines so elusive? HIV behaves unlike most other viruses in some important ways. Usually, when a person is infected with a virus, their immune system creates antibodies that target the bug. That’s usually the starting point for researchers, who work to develop drugs that can imitate that process (but without causing the recipient to develop a full blown reaction to the virus). What’s tricky about HIV, however, is that when a person is infected with the virus, that same process of developing antibodies isn’t triggered. “One of the reasons why it has been so difficult to make an AIDS vaccine is that the virus infects the very cells of the immune system that any vaccine is supposed to induce,” senior author Dr. Guido Silvestri, chief of microbiology and immunology at Yerkes National Primate Research Center [said in a statement](http://news.emory.edu/stories/2015/01/silvestri%5Fpnas%5Fhiv%5Fvaccine%5Ftarget%5Fcells/index.html). Still, expert hope the new vaccine trial will work better than earlier attempts. The new vaccine is based on a version tested in a clinical trial in Thailand, with results that were released in 2009\. The study showed that the vaccine was about 30% effective at preventing infection over 3.5 years. In the new trial, researchers hope to spur greater protection against the virus for longer. 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