Gilead Needs Insurers to Cover New HIV Prevention Shot. CVS Isn’t Paying. Executives at Gilead Sciences, the biotech behind a long list of HIV treatments and preventative medicines, have spoken with great optimism in recent weeks about the prospects that insurers will cover Yeztugo, their new HIV prevention shot .

CVS Health , which runs the largest U.S. pharmacy benefit manager, will not add Gilead Sciences' new HIV prevention drug to its commercial plans for now, a spokesperson told Reuters, despite the medicine's proven effectiveness.

Gilead Sciences (NASDAQ:GILD) saw its stock decline 2.7% in pre-market trading Thursday following news that CVS Health (NYSE:CVS) will not immediately add the company’s new HIV prevention drug, Yeztugo,