On Feb. 4, 2020, the Fred Hutchinson Cancer Research Center announced that a promising HIV vaccine trial was halted after it failed to show efficacy. The trial, launched in 2016, was expected to be unblinded and the results revealed in 2022.

The goal of the trial, known as Uhambo, was to test in South Africa the improved version of the Thai vaccine, which remains the only one ever shown to reduce HIV infection rates.