In 1983 and 1984 scientists established that HIV (the human immunodeficiency virus) causes AIDS, which had recently begun cropping up in gay men in California and New York. The discovery quickly led to predictions that a preventive vaccine would soon be on tap. Similarly, in 1996, after powerful drug combinations began forcing HIV down to undetectable levels in the blood, prominent HIV researcher David D. Ho of the Rockefeller University voiced optimism that attacking the virus early and hard could prove curative.