NHS Blood and Transplant has urged hospitals to issue an “Amber Alert” to restrict the use of O blood type to essential cases.

An increase in hospital demand for O blood type following a cyber attack and reduced collections due to unfilled appointments at donor centres, including Lancaster, have led to a severe blood shortage.

The health board has advised hospitals to use substitutions where clinically safe to do so.

They have also appealed to O-negative and O-positive donors to urgently book their appointments at donation centres.

Dr Jo Farrar, chief executive, said: “We urgently need more O group donors in Lancaster to come forward and help boost stocks to treat patients needing treatment.

(Image: NHS Blood and Transplant)

“Last month we saw an incredible response from donors who answered our call and filled up our centres, helping us meet the increased demands for blood throughout June.

“However, seven weeks on, the need for O negative blood in particular remains critical.

“We’re making an additional 1000 appointments per week available, please take a moment to go online and book.

“If you can’t find an appointment immediately, please book in for coming days, weeks and months.”

Register and book an appointment to donate via the GiveBloodNHS app or at www.blood.co.uk.

At present, national stocks of O-negative are 1.6 days, while overall blood stock across all types is 4.3 days.

On average, there are around 50,000 appointments to fill each week and more than 12,000 appointments are unfilled at donor centres across England in the coming fortnight, including 175 at Lancaster Donor Centre.

O-negative blood can be administered to anyone and is used in emergencies or when a patient’s blood type is unknown.

Despite constituting only eight percent of the population, O-negative blood makes up roughly 16 percent of hospital orders.

Dr Gail Miflin, chief medical officer at NHSBT, said: “Three blood donations are needed every minute in hospitals to deal with emergencies, childbirth and routine treatments.

“Blood only has a shelf life of 35 days so the NHS needs blood all year round.

“There are just under 800,000 regular blood donors, 108,000 of whom are O Negative.

“Ultimately, we need more people to be regular blood donors and come to one of our 25 donor centres.

“Women can donate once every four months and men can donate once every three months.”

Professor Sir Stephen Powis, national medical director at the NHS, said: “We’re seeing an increased demand for blood and shortages of stock so it’s important that donors come forward for appointments.

“With thanks to regular blood donors across the country, hospitals will continue to access stock when necessary and prioritise it for those who need it most.

“Patients should also continue to come forward for care if they need it – by using 999 in a life-threatening emergency or otherwise using 111 on the NHS App, online or by phone for other health concerns.”