Barts Health Trust , which runs The Royal London , St Bartholomew 's , Whipps Cross , Mile End and Newham hospitals , is investigating the breach . The trust said it could now rule out ransomware , in which email recipients are tricked Attack.Phishing into opening attachments which contain viruses , as the cause . It has not confirmed how much of its system was affected but said there was no sign that patient data was accessed Attack.Databreach . In a statement said : `` We are urgently investigating this matter and have taken a number of drives offline as a precautionary measure . `` We have tried and tested contingency plans in place and are making every effort to ensure that patient care will not be affected . '' The incident Attack.Ransom follows a similar attack Attack.Ransom on the Northern Lincolnshire and Goole Foundation Trust in October , when malware was used to encrypt files on the trust 's system and demand a ransom Attack.Ransom in order to access them again . The trust did not pay out Attack.Ransom , but was forced to cancel patient appointments while its systems were shut down to remove the virus