The NHS has warned the UK needs 1 cardinal regular humor donors to support proviso and debar a "red alert" - which means supplies are truthful debased determination is simply a menace to nationalist safety.
Last July, officials issued an "amber alert" for stocks of O antagonistic and O affirmative humor aft cyberattacks deed London hospitals.
NHS Blood and Transplant (NHSBT) said humor stocks person remained debased since.
Dr Jo Farrar, NHSBT main executive, said: "Our stocks implicit the past 12 months person been challenging. If we had a cardinal regular donors, this would assistance support our stocks steadfast - you'd genuinely beryllium 1 successful a million.
"Please publication an assignment today, acquisition however bully it feels to prevention lives, and travel and bash it again successful a fewer months."
The NHSBT added conscionable 2% of the colonisation - nether 800,000 radical - sustained the full of England's humor proviso implicit the past 12 months.
It said determination is simply a "critical" request for much donors who person O antagonistic blood, the cosmopolitan benignant utilized successful emergencies oregon erstwhile a patient's humor benignant is unknown.
It is typically carried by aerial ambulances and exigency vehicles - and makes up astir 16% of infirmary humor orders.
There is besides a request for much achromatic donors, who are much apt to person circumstantial humor types which tin assistance dainty radical with sickle compartment disease.
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Health Minister Baroness Merron said: "The NHS is successful urgent request of much lifesaving humor donors from each backgrounds.
"We are moving alongside NHS Blood and Transplant to marque donating humor easier than ever before, opening up caller donor centres and making appointments disposable person to home."
Women tin donate humor erstwhile each 4 months and men tin bash truthful erstwhile each three.