Google confirmed a "broad core algorithm update," with wide reports of massive impact. It rolled out over the period of about a week, but peaked on August 1-2. This update seemed to disproportionately affect sites in the health and wellness vertical, although large-scale impact was seen in all verticals.
- Google's August 1st Core Update: Week 1 (Moz)
- Google Medic Update: Google's Core Search Update Had Big Impact On Health/Medical Sites (SER)