even for people fully vaccinated. new york city s mayor, bill de blasio, says he s focusing on vaccinations but is following the cdc in issuing an indoor mask recommendation but not mandating them. we want to strongly recommend that people wear those masks indoors even if vaccinated. reporter: covid cases are surging, in large part due to the spread of the highly contagious delta variant. half the cases last week were reported in just five states. florida, texas, california, louisiana, and georgia. cases have gone up about fourfold in the last couple weeks, we re pushing up towards 100,000 cases a day now, and particularly so in those hot spots where vaccination rates are still quite low. reporter: hospitals in louisiana and mississippi, overwhelmed. health officials in austin, texas, preparing for the worst. it s scary, what we re seeing right now. we re seeing geometric climbs in our intensive care units.