A Promising HIV Vaccine Just Failed an Important Clinical Trial

Janssen's vaccine was ineffective at preventing HIV infections. While it's a setback, it's not the last option.

Jessica Rendall Wellness Reporter
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Jessica Rendall
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A gloved hand holing a vaccine vial against a light name background
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The HIV vaccine that excited the world by advancing to a late-stage trial is ineffective, according to an announcement Wednesday by Janssen, which is owned by Johnson & Johnson. 

There is no vaccine for HIV. Janssen's candidate, which was the only vaccine still being tested in a late-stage clinical trial, was found to be safe in approximately 3,900 participants, who were men who have sex with men and transgender individuals. But compared to a placebo, it was no more effective at preventing HIV infections. 

The trial began in 2019 and took place in Argentina, Brazil, Italy, Mexico, Peru, Poland, Spain and the United States. In partnership with Janssen, the study was also led by the National Institute of Allergy and Infectious Diseases arm of the National Institutes of Health, the US Army Medical Research and Development Command, and the HIV Vaccine Trials Network. 

"For our research partners and others who have waged a decades-long effort to develop vaccines to end the HIV/AIDS pandemic, these results are disappointing," Dr. Susan Buchbinder, HVTN co-chair of the study and director of Bridge HIV at the San Francisco Department of Public Health, said in a press release. "Although HIV continues to prove uniquely challenging for development of a vaccine, the HIV research community remains fully committed to doing just that, and each study brings us a step closer to this realization."

The trial was called Mosaico because the vaccine candidate was a "mosaic" vaccine – one meant to target a variety of strains that cause HIV infections. As reported by NBC, the failure of this vaccine wasn't necessarily unexpected, because a separate trial in women also found that the vaccine didn't offer protection against infection.

What's next? 

About 38 million people are living with HIV, or human immunodeficiency virus, according to the World Health Organization. The HIV virus attacks the human immune system and becomes life-threatening if not treated. Modern treatments, however, make it so those who are infected and start treatment will live a "normal" life with daily medications that keep the virus undetectable in their bodies. Other tools against the virus include PrEP medications for people who are higher risk of contracting HIV and post-exposure PEP medication for people who might've been exposed to HIV. 

The mosaic vaccine was a big deal because it was being tested for efficacy in a phase 3 trial, which requires a long development process to get to. While there are other vaccines in development, including some with mRNA technology such as Moderna's, it's too early to gauge effectiveness. 

One of the problems in finding an effective vaccine that works against HIV centers on how our immune systems respond to HIV compared with other viruses, according to the Broad Institute of MIT and Harvard: Our bodies are basically blind to the infection. The HIV virus also has a rapid reproduction rate and mutates quickly.

Vaccines act like natural infections in the way they stimulate our immune systems to make antibodies and attack a virus. But unlike when it's responding to a virus like smallpox or polio, the institute reported, our body is blind to HIV.

Dr. Anthony Fauci, who retired from his government posts in December but served as NIAID director during the AIDS crisis of the 1980s, told NBC the latest trial failure was "disappointing," but that there is still promise in that field. 

Fauci told the publication: "I don't think that people should give up on the field of the HIV vaccine."

The information contained in this article is for educational and informational purposes only and is not intended as health or medical advice. Always consult a physician or other qualified health provider regarding any questions you may have about a medical condition or health objectives.