SIOUX FALLS, S.D. (KELO) — This flu season in South Dakota, there have been at least 50 deaths related to the flu– That's the highest number in the past 7 years. At schools and day cares, it can be easy for sicknesses to spread. Little Tykes University in Sioux Falls knows that first-hand . "I think this year, we have been struck a little bit harder than we normally have, which is everybody has. There's places that have shut down entire school districts. We have seen a lot of illness from kids," Little Tykes University Owner, Corri Poore said. And with sick kids, often come sick staff members. House rejects veto override of child care bill This flu season's been so bad that Tykes to do something it's only done once before. "We actually had to close this facility down for a day because we just did not have the staff to be able to maintain," Poore said. They're not alone. Influenza numbers have been up across South Dakota. "We know it's about 20,000 cases in the state, which is the highest number we've seen over the last ten years," Chief Medical Officer of Sanford Health, Dr. Jeremy Cauwels said. Dr. Jeremy Cauwels says one of the biggest reasons for the increase in cases is the lack of people receiving a flu shot. "So we have seen a fairly pronounced correlation between people not getting their vaccine and the number of flu cases that we're seeing," Cauwels said. For the children at Little Tykes University, staff will continue to do what they can to keep the flu and other illnesses at bay. "When we do start to see things ramp up, then we are even more cautious, more vigilant in those cases. So, the surfaces that would have been cleaned anyway, we're going to clean them a little bit more, wiping down walls, door handles, things of that nature," Poore said. Dr. Cauwels says the flu shot is responsible for preventing 50% of hospitalizations of adults and over 70% for children. ...read more read less