HIV in the US vs in China

The class talked about HIV in the US, saying that it was first introduced from Africa to the gay communities of New York and San Francisco in the early 1980s. New York, Florida, Washington DC areas are still centers of disease. This surprised me a little because I thought it a lot worse. After the world war II and the vietnam war in the early 50s, there were a lot of American culture developing at that time when people just did a lot of sex and rock and free spirit. In china, it's still a big issue that people don't do random sex with strangers or even boyfriends.
When I came here, I felt like I was exposed to a culture with a lot of sexual appearances. It worries a little bit because researchers show that the menstration date for girls in America has reach to age 8 or 9. In China, the menstration date for girls, a lot of my friends, didn't have their period until they turned 12 to 15 years old.
That is probably why the HIV in China remains one of low prevalence overall, 0.1% among adults. The first case of HIV in China was a foreigner suddenly died in Beijing in 1985. Then five years later, a small group of people died because they didn't know aids could transfer through blood. It was probably some blood transfution that speard through needles. I think it's a good thing that at least China is not affected yet, knowing that my hometown is safe from now.