Some regional blood banks are putting out a call for donors. Christine Hayes from the Blood Center of Iowa says while some types are more common than others, a rare one is in top demand…O-negative. Hayes says only about 6-percent of the population has that blood type, yet in emergencies and traumas, it’s the first type given to patients. With that kind of imbalance between supply and demand, she says O-neg donors are asked to donate as often as they can. While it’s a “universal donor” type, caregivers prefer to give patients their own type of blood once they’ve matched it, so all types are needed. The blood bank’s seen a lower-than-normal donation level this season, and attributes it to cold and flu bugs hitting a little earlier than normal. Hayes says many loyal donors have been feeling “under the weather” this fall and aren’t donating, something that concerns the donor center since during the months late in the year donations normally go down, during a critical time. While the year-end holidays have many people too busy to give their regular donation, she says more are traveling and accident rates go up, increasing the demand for blood.