NHS hospitals across England have been hit by over 8,000 serious computer viruses in the last year.
As the government spends £12.7 billion moving patient records, prescriptions and X-rays to IT systems, it has emerged that the IT virus prevented those systems from working in many cases.
An investigation by More4 News found that 12 incidents had harmed patient care. In Maidstone and Tunbridge Wells, a virus attack prevented 100 users from being able to access the network. In Newcastle, a separate virus attack created so many problems that it resulted in a three week appointment backlog.
Other trusts affected include Grampian, Bradford Teaching Hospitals, Leeds Teaching Hospitals, Isle of Wight, Basingstoke and North Hampshire, and Poole.
Last November, Barts, the Royal London and the London Chest Hospital were hit by a virus that spread so quickly that it overloaded computer networks.
A number of the incidents could have been avoided with better anti-virus protection, the investigation found. A number of trusts told More4 News that their anti-virus systems were switched off, not properly applied, or that they had failed to allow automatic Microsoft Windows updates.
In Sheffield, 800 PCs were infected after one computer in an operating theatre had its security software switched off.