Some facts about HIV, from the Centers for Disease Control and Prevention:
—About 1.2 million people in the United States, and 35 million people globally, are estimated to be living with HIV.
—In the U.S., the CDC estimates nearly 13 percent of those people don't know they're infected.
—HIV is spread in the U.S. mainly through having unprotected sex or sharing injection-drug equipment with someone who has the virus.
—The CDC recommends that everyone between the ages of 13 and 64 have an HIV test at least once as part of routine health care, and that people seek out testing if they have such risk factors as having had sex with someone whose HIV status they didn't know.
—Cocktails of powerful medications have turned HIV into a manageable chronic disease for many people who can afford them. Those drugs also reduce the amount of HIV virus circulating in the body, what's called the "viral load," often to undetectable levels. That, in turn, reduces their chance of transmitting HIV to sexual partners, one reason that health officials urge early treatment.
—There is no vaccine. Latex condoms if used consistently and correctly are highly effective at preventing sexual transmission. Also, a daily pill sometimes is prescribed for healthy people to help prevent them from becoming infected by partners who have the virus, something called "pre-exposure prophylaxis."