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HIV vaccine shows promising results after human trials

A new vaccine for human immunodeficiency virus (HIV), under advance trial among humans, is likely to end a near 40-year quest to find an effective preventive measure for the infection, a new study claimed. 

In the first phase, the vaccine underwent trial among monkeys and humans. The clinical trial involving nearly 400 uninfected healthy adults showed production of an anti-HIV immune mechanism. Among monkeys, vaccine shielded 67 percent of them from the infection.

The trial for the vaccine’s efficacy has advanced to the next level; around 2,600 southern Africa women at the risk of acquiring HIV are being tested to determine the safety and efficacy of the vaccine candidate. 

Scientists have named the trial phase as HVTN705 or "Imbokodo." 

Previously, HIV vaccine development has focused on specific regions of the world. The study published in The Lancet takes different strains of the HIV virus and combines them to elicit immune responses against a wide variety of HIV variations. The experimental regimens tested in this study are based on ‘mosaic’ vaccines, researchers maintained. 

“These results represent an important milestone. This study demonstrates that the mosaic Ad26 prime, Ad26 plus gp140, boost HIV vaccine candidate induced robust immune responses in humans and monkeys,” explained Professor Dan Barouch, Director of the Center for Virology and Vaccine Research who led the study.  

HIV vaccine trials for efficacy have progressed after 35 years

Since the global surge of HIV/AIDS epidemic in the 1980s, only four vaccines have been tested in humans. 

In 2003, a trial of HIV vaccine—RV144— in Thailand was able to lower the rate of human infection by 31 percent. However, “the effect was considered too low to advance the vaccine to common use,” researchers said. 

The new vaccine, according to researchers, “is one of only five experimental HIV vaccine concepts that have progressed to efficacy trials in humans in the 35 years of the global HIV/AIDS epidemic,” they added. 

At present, more than 37 million people are living with HIV/AIDS infection.  Alarmingly, nearly, 1.8 million new cases are reported every year. 

The scientific community has been trying for a breakthrough for decades to develop a HIV vaccine with a robust efficacy. One of the major challenges for HIV vaccine development has been the lack of direct comparability between clinical trials and pre-clinical studies. 

Barouch led a team, in 2015, to deal with the hurdles,  he evaluated the leading mosaic vaccine candidates in parallel clinical and pre-clinical studies. The study aimed to identify the optimal HIV vaccine regimen to advance into clinical efficacy trials.

“The challenges in the development of a HIV vaccine are unprecedented, and the ability to induce HIV-specific immune responses does not necessarily indicate that a vaccine will protect humans from HIV infection.”

The trial recruited 393 healthy participants from East Africa, South Africa, Thailand, and the USA. They were randomly assigned to receive either one of seven vaccine combinations or a placebo and were given four vaccinations over the course of 48 weeks. 

To "boost" the level of the body's immune response, volunteers were given two additional vaccinations at weeks 24 and 48. “These results should be interpreted cautiously,”  Barouch warned. 

“It remains to be determined whether improved efficacy over RV144 will be achieved by either of the present efficacy trials,” Dr. George Pavlakis and Dr. Barbara Felber from the National Cancer Institute at Frederik, Maryland, cautioned.

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