In South Africa, trials of a new H.I.V. vaccine have been stopped because it's not working. Researchers are frustrated, but not giving up. 
“We hoped this vaccine candidate would work — regrettably, it does not,” said Dr. Anthony S. Fauci, director of the National Institute for Allergy and Infectious Diseases, which conducted the trial.
Another AIDS vaccine trial fails
Another #HIV Vaccine Fails a Trial, Disappointing Researchers: After 30 years of research, still no viable vaccine candidate via #AIDS