A large trial for a vaccine against the HIV virus, which is responsible for AIDS, started in 5 countries in sub-Saharan Africa in late 2017. The study is officially called HVTN 705, or Imbokodo.
The vaccine requires 4 injections within a year, then researchers will follow up for the following two years to test whether the vaccine regimen works. Results for the vaccine study are expected by 2021.
If the vaccine meets the 50 percent threshold, it will be considered sucessful and this question will be resolved as "Yes".