about a drunken attacker in Germany who stabbed 28 people (no fatalities, although 15 victims were taken to hospitals with critical wounds) following the dedication of Berlin's new train station. All of the victims were receiving HIV medication after it was learned one the the people stabbed was HIV positive. According to the article there was about a 3 in 1,000 chance that a victim could be infected after being stabbed with the contaminated knife. The prophylaxis is supposed to reduce the odds by an additional 80%.
While some NGO field offices have HIV prophylaxis on hand and/or SOPs in place to administer it following the sexual assault of a staff member, I've never seen its use recommended in a safety or security plan following an incident where multiple people are stabbed, slashed or chopped with the same edged weapon. Something to consider and remember, especially if you're working in a blade-oriented culture.