J&J’s HIV Vaccine Results Disappoint, Trial Halted But Search Continues

Johnson and Johnson has pulled the plug on its HIV vaccine trial after it was clear the shot did little to prevent HIV. The Phase 2 Imbokodo trial, which commenced in 2017, enrolled over 2,600 women in southern Africa who were at high risk of contracting HIV.

Besides J&J, the study had the backing of the National Institute of Allergy and Infectious Diseases (NIAID), the Bill & Melinda Gates Foundation, and the HIV Vaccine Trials Network.

Over the course of a year, participants received four shots, two of J&J’s vaccine, and two boosters containing HIV protein formulations designed to trigger the immune response. The study results revealed the vaccine was only 25% effective — falling short of the goal of 50% efficacy set by the researchers.

The silver lining is that the vaccine was safe. No serious adverse events occurred during the trial, it was reported. 

Blame the Virus, Not the Vaccine

J&J’s HIV vaccine technology uses the same adenovirus — a kind of common cold virus that’s been modified to not replicate in the body, as that found in their Ebola and COVID-19 vaccines.

Those vaccines were highly effective in preventing the respective diseases, so what went wrong in the case of HIV?

The fault lies not in the vaccine but in the elusiveness of the virus. HIV infects the immune cells of the body and uses many mechanisms to evade detection and destruction.

A Series of Unfortunate Setbacks 

Since HIV’s discovery in the 1980s, there has been a worldwide race to develop a vaccine that prevents viral infection. While effective treatments and preventative methods and medicine have been developed, a vaccine was still considered critical in winning the fight against HIV.

There had been many trials and just as many failures. Merck scrapped a Phase 2 clinical trial in 2007 after its STEP vaccine failed to prevent HIV infection. In 2009, the Thai military backed a study known as RV144 which investigated whether a combination of two vaccines ALVAC and AIDSVAX was effective in preventing HIV. Results reported an efficacy of 31%, which was deemed too low for the trial to continue.

Other Trials to Carry On 

Despite the latest setback, scientists remain hopeful.

“This is in no way the end of the search for an HIV vaccine,” said Mitchell Warren, executive director of HIV prevention advocacy organization AVAC. “We still hope for a positive outcome from the ongoing Mosaico and PrEPVacc studies.”

The Phase 3 Mosaico trial has been deemed different enough to be worth continuing. It is enrolling 3800 homosexual and transgender men across Europe and the Americas. The intervention includes 4 injections of the vaccine and 2 injections of the booster, which uses different protein formulations than that of the Imbokodo trial. 

The PrEPVacc study combines HIV vaccine candidates with PrEP (pre-exposure prophylaxis), an oral pill that has up to 99% efficacy in preventing HIV when taken daily. The African-led study is recruiting over 1600 participants that are at high risk of HIV infection.

In a separate development, Moderna will begin human trials of its HIV vaccine next month. The vaccine uses the same mRNA technology as its highly successful COVID-19 vaccine.

Author

Joy Lin

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