Knowing you have HIV decreases transmission by 90%. Giving antivirals decreases transmission by 99%. Back in the early 2000 I saw a paper saying we could make HIV tests for 10 cents a person if we wanted to produce enough for every person on the planet (0.1810^9= $800 million). That was something that could have been done back then. $40 a vaccine would be a price tag of $320 billion