The American Red Cross is urging people to donate blood as the organization faces its worst national blood shortage in over a decade.

The shortage has forced health care providers to decide which patients will get life-saving transfusions and which have to wait for the supply to be replenished. The Red Cross has had to limit blood supplies to hospitals, and there have been periods with less than a one-day supply of critical blood types in recent weeks, the agency said.

The organization made a similar call for blood donations in December amid low donor turnout.

On its website, the Red Cross said much of the current blood shortage is driven by the ongoing COVID-19 pandemic.

On top of a 10% drop in blood donations since March 2020, blood drives continue to be canceled because of illness, staffing shortages and weather-related issues, the Red Cross said.

As COVID-19 has affected schools and universities, blood supplies have been impacted, too. Students accounted for about a quarter of all blood donations in 2019 but have made up only 10% during the pandemic, the Red Cross said. College and high school blood drives dropped by 62% since the COVID-19 pandemic began, the organization said.

While all blood types are needed, people with Type O blood are especially encouraged to donate. Type O-negative is the universal blood type, while Type O-positive can be given to anyone who is Rh positive.

Anyone 16 or older, at least 110 pounds and in good health can donate blood. More specific eligibility criteria can be viewed online.

Appointments can be made online, through the Blood Donor App, or by calling 1-800-733-2767.

People can return every 56 days to donate, and scheduling repeat appointments is encouraged.

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