What's now key for VBIV stock is how Sci-B-Vac fares against Dynavax's (NASDAQ: DVAX ) Heplisav-B. According to a Seeking Alpha contributor, Heplisav-B's key selling point is that it's a two-dose vaccine ., while VBIV plans to market its vaccine as a three-dose treatment. But Heplisav-B has had its own headwinds. Rejected twice due to safety concerns by the FDA, Heplisav-B was finally approved in late 2017.