This article originally appeared on niaid.nih.gov. To see the full article, click here.

The National Institute of Allergy and Infectious Diseases (NIAID), part of the National Institutes of Health, has stopped administration of vaccinations in its HVTN 702 clinical trial of an investigational HIV vaccine. This action was taken because an independent data and safety monitoring board (DSMB) found during an interim review that the regimen did not prevent HIV. Importantly, the DSMB did not express any concern regarding participant safety.

The Phase 2b/3 study, named HVTN 702 or Uhambo, began in 2016 and is taking place in South Africa. It was testing an investigational prime-boost vaccine regimen based on the only vaccine regimen ever to show protection from HIV—the regimen tested in the RV144 clinical trial in Thailand led by the U.S. Military HIV Research Program and the Thai Ministry of Health. For HVTN 702, the vaccine regimen was adapted to the HIV subtype Clade C most common in southern Africa, where the pandemic is most pervasive.

“An HIV vaccine is essential to end the global pandemic, and we hoped this vaccine candidate would work. Regrettably, it does not,” said NIAID Director Anthony S. Fauci, M.D. “Research continues on other approaches to a safe and effective HIV vaccine, which I still believe can be achieved.”

The HVTN 702 study enrolled 5,407 HIV-negative volunteers at 14 sites across South Africa. The study population consisted of sexually active men and women aged 18 to 35 years. The study volunteers were randomly assigned to receive either the investigational vaccine regimen or placebo injections. Study participants received six injections over 18 months. As with all NIAID-sponsored HIV prevention trials, the safety of HVTN 702 study participants was closely monitored throughout the trial, and participants were offered the local standard of care for preventing HIV, including access to oral pre-exposure prophylaxis (PrEP).

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