The NHS is urging Bradford residents to donate blood over the half-term and Halloween period.
Bradford Donor Centre, in Manor Row, has around 80 appointments available this week, as well as hundreds more in the coming weeks.
NHS Blood and Transplant needs donors to fill empty slots to sustain blood stocks over the winter period.
An Amber alert, issued in July to indicate severely low stocks of O negative blood, remains in place.
More donors from the black community are particularly needed, as they are more likely to have the blood subtype Ro used to treat sickle cell.
The NHS reportedly only has enough donors to supply half the amount of blood needed by sickle cell patients, with the rest needing to be substituted with O negative.
People with O negative and B negative blood are also urged to donate.
Mark Chambers, director of donor experience at NHS Blood and Transplant, said: "Halloween is all about fake blood and gore.
"But we need real blood – and lots of it – to save lives at Halloween and all year round."
To book an appointment visit www.blood.co.uk, use the GiveBlood app, or call 0300 123 23 23.
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