UnitedHealthcare, one of the largest health insurance companies in the nation, notified plan members that starting September 1, it will no longer cover Descovy as pre-exposure prophylaxis (PrEP) to prevent HIV, reports MedCity News.

The announcement arrives as a low-cost generic version of Truvada as PrEP will become available September 30.

Approved as PrEP last October, Descovy is an updated version of Truvada, which was approved as PrEP in 2012. Both tablets consist of two meds: emtricitabine and a version of tenofovir. Descovy contains tenofovir alamenafide, while Truvada contains tenofovir disoproxil fumarate, the older of the two.

When taken daily as directed, both meds are highly effective at preventing HIV. Both are manufactured by California-based drugmaker Gilead Sciences. Both are also used as part of HIV treatment regimens by some people living with HIV. Descovy, the newer med, is easier on the bones and kidneys (especially when it’s used for treatment), but both are safe for most PrEP users.

According to MedCity News, UnitedHealthcare will provide the generic version at no out-of-pocket cost. Plan members who prefer Descovy will have to get prior authorization, though the med may come at a higher price. (When Descovy hit the market, it was listed at the same price as Truvada: $1,758 a month.)

Scientists estimate PrEP to be about 99% effective among men who have sex with men and to be greater than the current 88% to 90% estimate for heterosexual men and women. For more details, see “How Well Do U=U and PrEP Work? The CDC Updates Its Answers.” To learn more about these PrEP meds, see “What’s the Different Between Truvada and Descovy for PrEP?”