Gilead Sciences announced Wednesday that a generic version of Truvada will be available in September 2020, one year earlier than expected. Truvada is the pill used for HIV pre-exposure prophylaxis, or PrEP. When taken daily, Truvada prevents HIV transmission.

"Gilead reached an agreement with Teva Pharmaceuticals in 2014 to allow the early launch of a generic version of Truvada into the market in 2020, a year earlier than required," wrote Douglas Brooks, Gilead's executive director for community engagement, in an email shared with NBC News by the advocacy group PrEP4All.

The information about generic Truvada is also disclosed on page 35 of a Gilead SEC filing released Wednesday morning. While a month’s supply of generic Truvada is available in countries around the world for as little as $70, in the United States a month’s supply sells for $1,600 to $2,000, and activists have mounted a pressure campaign to force Gilead to make the drug more widely available in order to curb the global HIV epidemic.

President Donald Trump’s “Ending the HIV Epidemic” plan, announced at this year’s State of the Union address, will rely heavily on Truvada in order to stem the spread of the virus. But Truvada’s high price threatened to make the plan extremely expensive, activists said.

Previously, in a phone call with investors in the second quarter of 2017, then-Gilead CEO John Milligan said, "We don't expect generic Truvada in the United States until 2021."