Officials in Washington State report a local man has contracted HIV while taking PrEP. Not much has been revealed about the unnamed patient, including whether he took the medication consistently, but the Seattle & King County's Public Health Department reports he was infected with a rare strain of HIV resistant to both medications in Truvada, the drug's commercial name.

If taken correctly, PrEP can reduce the risk of HIV by 90% (though studies have reported numbers as low as 86% and as high as 99%). Of the hundreds of thousands of people taking PrEP worldwide, there have been only five reported cases of someone testing positive.

Last year, an Australian man participating in a PrEP clinical trial became infected with a drug-resistant strain of HIV.

A Dutch man on PrEP also tested positive in 2017, but doctors theorize his unusually high number of sex partners (50 a month on average), the frequency with which he had condomless sex, and the presence of other STIs in his system may have been unique factors.

In 2015, the CDC recommended that 1.2 million gay and bisexual men, or about one in four, be on PrEP. As of early 2017, only 136,000 Americans were taking Truvada.

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