An urgent appeal for Londoners to donate blood has been launched amid a “perfect storm” affecting blood stocks.
NHS Blood and Transplant said O Negative blood types were particularly needed - and issued an ‘amber alert’ to hospitals ordering them to restrict the use of that blood type where safe to do so.
The O Negative blood type is known as the universal blood type, meaning it is critical in emergencies or when a patient’s blood type is unknown.
Increased demand for O-type blood from hospitals following a crippling cyber attack which affected major London hospitals and unfilled appointments has caused stocks of blood to fall to “unprecedentedly low levels”.
An NHS spokesperson said national stocks of O Negative blood were just 1.6 days and overall national stocks of blood across all types is 4.3 days.
NHSBT Chief Executive Dr Jo Farrar said: “We urgently need more O group donors in London to come forward and help boost stocks to treat patients needing treatment.
“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.”
On average, there are around 50,000 blood donor appointments to fill each week.
But there are over 12,000 appointments still to fill in donor centres across England over the next two weeks including 5,000 across London donor centres.
Around eight per cent of the population have Type O Negative blood, but it accounts for around sixteen per cent of hospital orders.
The cyber attack in June on pathology services provider Synnovis by Russian cyber gang Qilin caused thousands of appointments to be cancelled or postponed across the two most affected trusts, King’s College Hospital NHS Foundation Trust and Guy’s and St Thomas’ NHS Foundation Trust.
Stocks are also lower on average in summer because holidays and travel abroad can reduce people’s availability, while unexpectedly hot days can see an increase in people unable to give blood due to a lack of hydration or lower iron levels.
NHSBT’s Chief Medical Officer, Dr Gail Miflin, 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.
Officials stressed that despite the low availability, hospitals will continue to carry out urgent, emergency or trauma surgery, cancer surgery, transplant surgery and blood transfusions to treat people with long term conditions.