The Food and Drug Administration just approved a new drug that can be used as PrEP (pre-exposure prophylaxis) to prevent the transmission of HIV.

PrEP is a medication regimen that has been shown to be 99% effective in preventing HIV transmission if taken daily. Up until now, the only drug approved for that use is Truvada, which was approved in 2012.

Related: PrEP users face rampant stigma & slut-shaming, study finds

On Thursday the FDA approved Descovy as a medication to prevent the transmission of HIV in men and transgender women who have sex with men. The approval did not extend to use by people assigned female at birth due to a lack of research into effectiveness in this population.

Descovy has been shown in clinical trials to be less harmful to users’ kidneys and bones than Truvada when used over a long term, and it has been shown to be as effective as Truvada in preventing the transmission of HIV.

The pharmaceutical corporation behind both of them – Gilead – is expected to try to move people from Truvada to Descovy this year because Truvada’s patent runs out next year, which means generic versions of Truvada should be available.

“The key will be the extent to which Gilead can transition the market to branded Descovy ahead of Truvada’s genericization in around one year,” Brian Abrahams, analyst for RBC Capital Markets, told Reuters.

People who work to reduce HIV transmission say there’s little need to push Descovy in a majority of cases, especially since Truvada is expected to get much cheaper as the generic market opens.

“Based on the science that we have seen thus far, there is no indication that everyone needs to be taking Descovy,” Tim Horn, director of medication access and pricing at the National Alliance of State and Territorial AIDS Directors, said last month as FDA approval was imminent.

“We see no reason to push back against commercial payers or Medicaid programs that would move to prefer generic Truvada” as long as the people who have a specific need for Descovy can access it, Horn added.