The American Red Cross is facing an "emergency blood shortage" as it experiences the lowest number of people giving blood in two decades.

The big picture: It's not the first time the nation's largest blood supplier has warned of a dangerously low supply, which can have devastating consequences.

State of play: The Red Cross is urging people to donate because blood and platelets are currently needed to help alleviate the shortage and ensure lifesaving medical procedures can move forward.

• The Red Cross experienced a nearly 7,000-unit shortfall in blood donations between Christmas and New Year's Day alone, the nonprofit told Axios.

What they're saying: "One of the most distressing situations for a doctor is to have a hospital full of patients and an empty refrigerator without any blood products," Dr. Pampee Young, chief medical officer of the Red Cross, said in a statement.

• "A person needs lifesaving blood every two seconds in our country — and its availability can be the difference between life and death, however, blood is only available thanks to the generosity of those who roll up a sleeve to donate," Young added.

Why is there a shortage?

The intensified need for donors is because the nation is facing the lowest number of people giving blood in 20 years, per the nonprofit, which means shortages are not uncommon in the U.S.

• The number of people donating blood through the Red Cross has fallen by about 40% over the last two decades.
• Even small disruptions to blood donations, like the one during the holiday period this year, can have an immense impact on the availability of blood products and major consequences for those in need of emergency blood transfusions.
• The need for blood is constant, and because it cannot be stockpiled, factors such as fewer donations amid consistent hospital demand can have an impact on the supply, the Red Cross said.

Why aren't people donating as much anymore?

There are several factors that have contributed to the decline in donors.

• One is that the way people engage in their communities has evolved over the past two decades, the nonprofit said, adding that COVID-19 accelerated those changes.

By the numbers: The number of people giving blood to the Red Cross has fallen by more than 300,000 since 2019 due to the pandemic, per the organization.

• As more people began to work and conduct their lives remotely, it became more challenging to meet people where they are with convenient blood drives, the Red Cross said.

Additionally, before to the pandemic, there were changes in eligibility guidelines, like the minimum hemoglobin thresholds, which resulted in more donor deferrals, especially among those 16 to 18 years old.

• Even before that, there were changes in blood transfusion protocols at hospitals that impacted the demand for blood.

Why are blood donations vital?

The blood collected by the Red Cross is used to meet the needs of accident and burn victims, heart surgery and organ transplant patients, and those receiving treatment for leukemia, cancer or sickle cell disease.

• "While the Red Cross prioritizes the needs of area hospitals first, it also provides blood throughout the country, wherever there is a need," the nonprofit said.

The bottom line: If the necessary blood products aren't readily available, doctors may have to forego performing serious procedures as well as postpone elective surgeries.

• "We are doing everything we can to minimize any impact of this shortage on hospital patients," the Red Cross said.

Go deeper: Red Cross implements end to blood donor restrictions on gay, bisexual men