New numbers on the global AIDS epidemic are showing some big successes, but also some tragic failures. There are fewer deaths and new infections. But only half the children with HIV, the virus that causes the disease, are getting treatment. The United Nations’ AIDS agency issued the report Monday at the start of an international conference on the disease. New infections are down 23% and annual AIDS-related deaths are down 39% since 2010. But that’s far short of goals set for this year, and children are lagging behind. The coronavirus pandemic also is hurting access to care and threatens to undo much of the progress that’s been made.