The recommendation from the Southern Nevada Health District isn’t a requirement. But it affects casinos, concerts and clubs where business has boomed since restrictions were lifted and the state fully returned pandemic control measures to counties about seven weeks ago. “Both vaccinated and unvaccinated individuals should wear masks when they are in crowded public settings ... such as grocery stores, malls, large events and casinos,” Dr. Fermin Leguen, the region’s chief health officer, told reporters. He said the district doesn’t have authority to make masks mandatory, leaving that question to the state, county and cities... The mask recommendation in Las Vegas came after Nevada health officials on Thursday reported 938 new cases of COVID-19 statewide — the biggest one-day coronavirus case jump since February — and 15 new deaths.