While only 7 percent of people in the U.S. has type O negative blood, it saves more lives than any other type because it can be used in all blood transfusions. And the American Red Cross has less than a two-day supply left.

On the average, emergency rooms use 14 units of type O blood per every 100,000 people daily. They're currently working with six units until the supply runs out, according to a rep for the Red Cross. Although Spring typically sees a drop in blood donors, this year has seen an even steeper decrease as the organization has received 11,500 less units than usual, the rep says.

The Red Cross is hoping to bolster donations by offering a $5 Amazon gift card to anyone who gives blood through June 10th.
How often do you donate blood? Have you ever needed a blood transfusion?

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