The outcome of this critical vote was in serious doubt after the FDA released its briefing documents last Wednesday. Specifically, the agency pointed out that patients receiving Heplisav-B exhibited a higher rate of serious adverse effects in its latest phase 3 trial, compared with those receiving GlaxoSmthKline 's Engerix-B. Although the data was far from conclusive, this safety concern was enough to cause Dynavax's shares to nosedive by double digits.