Pharma giant Johnson & Johnson announced yesterday that it was pulling the plug early on its latest trial after it became clear it wasn’t proving effective. Janssen, J&J’s research arm, partnered with the National Institute of Allergy and Infectious Diseases (NIAID).

A spokesperson for NIAID said, “It’s not the outcome we had hoped for, unfortunately. The development of a safe and effective HIV vaccine has been a considerable scientific challenge, but we will learn from this study and continue forward.”

HIV mutates rapidly and is skilled at evading the body’s immune system. As a retrovirus, it can hide in the very DNA of our cells. This makes it impossible for our own immune system to locate the virus. For this reason, attempts to produce a vaccine have so far failed. Although this latest formulation showed some efficiency in earlier trials, that effectiveness was clearly not good enough for experts to consider releasing it to the market.