So middle stage can last from several months to several years. So no visible symptoms, low levels of that virus. We have the presence of these antibodies and we have a very slow but very continual decline in the population of our helper T cells. So during the middle stage, the HIV continually but slowly begins to kill off these helper T cells. And the final stage, the late stage, this is when we actually are diagnosed with Acquired Immune Deficiency Syndrome. This is when our HIV begins to kill off the helper T cells at a very high rate and the population of helper T cells drops to very low amount.