Only 4 percent of sexually active men who have sex with men in the United States are on Truvada, a new study has concluded.

Truvada is a prescription only medication used to treat and prevent HIV/AIDS. In 2012, the FDA approved Truvada for preventative use, and recommended the form of pre-exposure prophylaxis (PrEP) for high-risk groups, including gay and bisexual men, to reduce the risk of infection.

A first-of-its-kind study conducted by the Williams Institute at the UCLA School of Law and published last week in the journal PLOS ONE shows a low rate of PrEP use in the United States, MedicalXpress reported.

“The extremely low rate of PrEP use, while not surprising given barriers to access in various parts of the country, is disappointing,” said Phillip Hammack, a psychology professor who led the study.

Hammack and his team also found that young gay and bisexual men (18-25) who are sexually active are not tested for HIV annually, as recommended by the Centers for Disease Control and Prevention (CDC). However, young men were more likely to be familiar with PrEP as HIV prevention than men aged 34-41.

“I worry especially about younger men who didn't grow up with the concerns of HIV and men of older generations did,” Hammack said. “The low rate of HIV testing probably reflects a degree of complacency and cultural amnesia about AIDS.”