The National Health Service (NHS) in England issued an urgent call on Monday for O-type blood donations following a ransomware attack that has disrupted blood matching tests for several healthcare organizations in London.

The attack last week hit Synnovis, a business providing pathology services for hospitals and local clinics in the capital. The Russia-based Qilin ransomware gang is suspected by officials to be behind the attack, according to sources briefed on the matter.

As a result of the cyberattack “hospitals cannot currently match patients’ blood at the same frequency as usual,” announced NHS Blood and Transplant on Monday. This means that hospitals are having to use more of their stocks of O-type blood, which is the safest to give to most other blood types.

“To support London hospitals to carry out more surgeries and to provide the best care we can for all patients, we need more O Negative and O Positive donors than usual,” said Dr. Gail Miflin, the chief medical officer at NHS Blood and Transplant.

Donors can currently book appointments at any of the 25 donation centers in England.

The ransomware attack on Synnovis has led to a critical incident being declared at the affected hospitals. Numerous patients have either had their appointments canceled or are being directed to other hospitals that then have to work at an increased capacity.

Medical students have also been asked to volunteer to work extra-long shifts, up to 12 hours at time, to help the affected hospitals, and warned they “should be prepared for extended periods on their feet.” A memo posted on social media warned: “The ripple effect of this extremely serious incident is felt across various hospital, community, and mental health services in our region.”

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Stephen Powis, the medical director for NHS England, said: “NHS staff are continuing to go above and beyond to minimise the significant disruption to patients following the ransomware cyber-attack on Synnovis earlier this week.”

Although urgent and emergency services are available as usual, “a number of operations and appointments have been postponed or diverted to other neighbouring hospitals not impacted by the cyber-attack, as we prioritise pathology services for the most clinically urgent cases,” said Powis.

“To help London staff support and treat more patients, they need access to O Negative and O Positive blood, so if one of these is your blood type, please come forward to one of the 13,000 appointments currently available in NHS Blood Donor Centres.”

NHS England stated: “At present the full extent of the attack, as well as the impact upon data, is not known. Once further information is known we will report accordingly in line with Information Commissioner’s Office requirements.”

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