LANSING, Mich. (Michigan News Source) — A cold winter and a rough flu season did more than cancel plans: they thinned the blood supply.

The American Red Cross is warning of a “severe blood shortage” after donations nationwide dropped 35% in December, cutting roughly 40,000 units from supply. 

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Patients use more than 42,000 units of blood each day, officials said. Moreover, because blood has a 42-day shelf life, shortages can lead to postponed surgeries and treatment delays.

The Red Cross blamed the drop on extreme cold and what it called the “worst flu season in nearly 20 years,” which forced hundreds of canceled blood drives, including several in Michigan.

Meanwhile, the Red Cross is hoping a Super Bowl LX giveaway—tied to donations through Jan. 25—helps keep supplies from running dry.

As Michigan Medicine physician Dr. Jensyn K. Cone Sullivan put it, a reliable blood supply “truly is the difference between life and death for many patients.”