A spokesman for the trust said: "Barts Health staff have been working tirelessly over the weekend, using tried and tested processes to keep patients safe and well cared for".
The National Cyber Security Centre has been coordinating the State's response to the threat from the fast-spreading malicious software and has issued a series of advisory notices to Government departments and agencies.
Proofpoint and a British cybersecurity researcher teamed up on Friday to derail the attack that was said to strike at least 100,000 organisations in 150 countries.
"The governments of the world should treat this attack as a wake up call", Microsoft's president and chief legal officer, Brad Smith, wrote in a blog post about what is being called the largest ransomware attack ever.
The virus is then able to encrypt files and block user access to them, displaying a pop-up window onscreen telling users they have been blocked and demanding payment.
Blackpool Teaching Hospitals NHS Foundation Trust, NHS Blackpool Clinical Commissioning Group (CCG) and NHS Fylde and Wyre CCG are still experiencing IT problems.
More than 200,000 victims in around 150 countries have been infected by the ransomware which originated in the United Kingdom and Spain on Friday, before spreading globally.
The attack has left 47 NHS organisations affected with malware in their system, ranging from hospital trusts to commissioning support units.
NHS Shetland appears to have been one of only three health boards in Scotland to have been unaffected by a worldwide cyber attack on Friday.
A cyber virus which caused turmoil within the NHS could have been much worse, a computer expert at the University of Sheffield has claimed.
He added: "The trust's security measures that we have got in place are stable and still holding firm".
NHS Digital has confirmed to Sky News that the patch was made available on its cyber portal on 25 April, and a link sent to NHS IT staff on 27 April.
"I expect our services to be operating as normal from Monday (15 May 2017) including our community clinics".
A spokesman for the trust said: 'The NHS is now experiencing issues due to the recent cyber-attack on May 12.