MUSC reported this week that COVID cases jumped by 26%. This is on top of the 121% increase officials reported the previous week. Caption: MUSC reported this week that COVID cases jumped by 26%. (WCIV) Related:CDC urges indoor masking as COVID cases surge nationwide. Cases in the Tri-County area are now 21 per 100,000 people in the population. Doctor Michael Sweat told ABC News 4 these estimates are actually an undercount since more people have started doing at-home tests.