Arizona is facing a widespread blood shortage as the holiday and flu seasons make it harder for people to donate.

Sue Thew is with Vitalant, the blood provider that supplies 90% of blood in Arizona. She says the situation is dire and donors are needed as soon as possible.

“Right now we have a critical shortage for type O-positive and O-negative blood, those are the universal blood types used in emergencies and traumas," she said. "While we strive to keep a four-day supply of blood on the shelves, right now we have just under a one-day supply of O-negative and a two-day supply of O-positive.”

Blood donations spike any time there’s a natural disaster or mass casualty. But blood only keeps for about 42 days, and during the holidays and flu season, supplies can dwindle to dangerously-low levels.

Some patients like McKindree Patton need regular blood transfusions. She had a condition that prevented red blood cells from regenerating.

“I got blood transfusions every four weeks to live, and then four years later, I relied on blood for four years, then when I was 16 I had a bone marrow transplant," she said. "I relied on hundreds and hundreds of blood transfusions to live.”

Thew says O-negative blood is the most needed - but anybody who meets the eligibility requirements is encouraged to donate.