The British government said 48 of the 248 health service trusts in the United Kingdom were impacted by Friday's attack.
It also asked patients with pre-booked GP appointments to "please bring with you any medications, letters or paperwork you already have".
Numerous nearly 8,000 doctors' surgeries in England were also affected, warning of delays as doctors reverted to paper records and appointments.
"Bearing in mind the impact of the global cyber attack we would urge people to be patient with staff who may still be dealing with disruption to their systems". Still, he said, "Microsoft needs to admit that the 20th century is over, it's a much more hostile environment, and the hobbling NSA won't make us any safer."Under former President Barack Obama, the USA government created an inter-agency review, known as the Vulnerability Equities Process, to determine whether flaws should be shared or kept secret.White House cyber security coordinator Rob Joyce, who previously worked in the NSA's elite hacking squad, told a Reuters reporter in April that the Trump administration was considering how to "optimise" the Vulnerability Equities Process, but he did not elaborate.The White House did not respond to a request for comment about the status of the review process".
In Britain, the National Cyber Security Center said it is "working round the clock" with experts to restore vital health services.
Scottish targets included 11 health boards, NHS National Services and the Scottish Ambulance Service.
Russia's interior ministry said some of its computers had been hit by a "virus attack" and that efforts were underway to destroy it.
This attack, dubbed WannaCry, was the real deal, and knowing everything you can about this cyber attack is vital to protecting yourself from one in the future.
"This attack provides yet another example of why the stockpiling of vulnerabilities by governments is such a problem", Microsoft President and Chief Legal Officer Brad Smith said in a blog post on Sunday, comparing the recent leaks of NSA and Central Intelligence Agency hacking tools to, in the real world, the theft of cruise missiles.
Riverbank IT Management managing director Malcolm Newdick said: "Last week's ransomware attack was the most risky malware attack we have seen".
Britain's National Crime Agency (NCA) also said it had seen no evidence of a "second spike in WannaCry ransomware attacks" by midday, but warned that another attack could still happen. Senior security staff reportedly held another meeting in the White House Situation Room on Saturday. Nonetheless, officials and security firms seemed optimistic, telling news outlets that the spread was starting to slow.
"The growth rate of infected institutions on Monday has slowed significantly compared with the previous two days", said Chinese Internet security company Qihoo 360.
Over the weekend, Qihoo reported that the ransomeware attack infected almost 30,000 groups by Saturday night.
"With access to and the use of vast quantities of personal data, public bodies must have in place robust data protection plans, ensure access to expert support and not to cut cyber security resources when efficiencies are needed elsewhere". Lord added that "one customer said they actually forgot they were being robbed".
Global investigators hunted Saturday for those behind an unprecedented cyber-attack that affected systems in dozens of countries, including at banks, hospitals and government agencies, as security experts sought to contain the fallout.
Who perpetrated this wave of attacks remains unknown.