Demand for blood is up 10% in the United States, and some U.S hospitals are postponing surgeries due to shortages.

Experts say the situation is a consequence of the COVID-19 pandemic, CBS News reported. Before COVID-19 shutdowns, schools accounted for 25% of collected blood.

NYU Langone Health in New York City came close to delaying scheduled surgeries, surgeon-in-chief Dr. Paresh Shah said.

"There's this huge backlog of operations that really needed to get done," Shah told CBS News. "We were down to such a low inventory of blood that if we had one major transfusion event, we would have been depleted completely."

Some U.S. blood centers have only a one-day supply. OneBlood, the Southeast's largest blood center, is struggling to deal with the blood shortage.

"It's a 24/7 operation," OneBlood's Susan Forbes told CBS News. "The donors are not in the traditional locations anymore. We lost large corporations, religious organizations, movie theater drives, festivals that were taking place ended."