More than a million people in the United States are living with HIV, according to the Centers for Disease Control and Prevention, and nearly 20 percent don't even know they are infected. This year alone, more than 15,000 Americans will die from some complication related to HIV or AIDS.
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Yet it's not all bad news. Since the HIV/AIDS epidemic began more than 30 years ago, prevention and treatment have improved significantly. An HIV diagnosis is no longer an automatic death sentence, and people with the virus are living longer and better than ever before.
Join Dr. Richard Besser, ABC News' chief health and medical correspondent, and a host of experts, advocates and patients for our tweet chat at 1 p.m. to discuss advances in HIV and AIDS. During the chat, you can follow the live blog below for even more information. Mobile users can use this link for the live blog.