Hospital bosses in East and North Herts say they've already brought in changes to their IT systems following a massive cyber-attack...
The Lister, Hertford County and New QEII hospitals were all affected in May, with appointments having to be cancelled and some ambulances diverted.
At the Lister, over 5,000 pieces of diagnostic equipment that were linked into the IT systems had to be individually analysed and tested. No computer could be turned back on until they had been fully checked over.
As an independent investigation by the National Audit Office is published, the NHS Trust says it has strengthened computer firewalls and overhauled how security updates are applied and managed.
The East and North Herts NHS Trust's chief executive, Nick Carver, said: "We have not waited for the National Audit Office's report, which has been focussed on the NHS as a whole, to be published to start making improvements to our cyber security that were possible within the resources available.
Like NHS organisations across the country, we will now review the recommendations set out in the NAO report to see what more needs to be done".
(BELOW: The Hertford County Hospital)
Sir Amyas Morse, the head of the NAO, said: "The WannaCry cyber attack had potentially serious implications for the NHS and its ability to provide care to patients. It was a relatively unsophisticated attack and could have been prevented by the NHS following basic IT security best practice.
There are more sophisticated cyber threats out there than WannaCry so the Department (of Health) and the NHS need to get their act together to ensure the NHS is better protected against future attacks".
The NAO found that almost 19,500 medical appointments, including 139 potential cancer referrals, were estimated to have been cancelled, with five hospitals having to divert ambulances away. Computers at 81 health trusts across England - a third of the 236 total - were infected along with computers at almost 600 GP surgeries.
Speaking to BOB fm at the time, Zaina Amri - who'd been called in unexpectedly on Sunday for early blood tests ahead of her c-section - said it was unsettling so close to her delivery date: "It is a bit scary. What is going to happen if there is maybe a problem with the theatre and we are not going to be able to go in on Tuesday? I am thinking of myself and the baby".
Natalie Reid was visiting her 85-year-old grandmother, who was stuck on a ward waiting for blood test results, before she could be treated for problems with her liver and kidneys: "My nan is very precious to me and the fact that this has happened and has affected the way she can be treated is quite disgusting really.
I feel sorry for the IT guys who have been called in who are under massive pressure, they are not doctors and nurses, but now it is down to them as to whether people are going to live or die or get the treatment they need".
Public Accounts Committee chair Meg Hillier also warned: "The NHS and the Department need to get serious about cyber security or the next incident could be far worse".
In a statement the Department of Health said: "The NHS has robust measures in place to protect against cyberattack. Since May we have taken further action to strengthen resilience and guard against future attack, including new, unannounced cyber security inspections by the Care Quality Commission, £21m in funding to improve resilience in trauma centres, and enhanced guidance for trusts".
More than 300,000 computers in 150 countries were infected with the WannaCry ransomware. It affected organisations from government agencies and global companies by targeting computers with outdated security.