Home Secretary Amber Rudd said that a million people were treated on Monday, with GP surgeries working hard to ensure as few patients as possible are affected.
"This is a sophisticated attack in terms of how it goes about attacking systems but relatively simple in terms of what it does, which is to scramble data and charge a ransom for victims to unscramble that data".
One theory suggested that 90 percent of NHS trusts across the United Kingdom were using Microsoft's 16-year-old OS Windows XP, which could leave them susceptible to attacks.
The government is targetting small businesses in it's mitigation messaging which it believes are most at risk from the ransomware.
A cyber virus which caused turmoil within the NHS could have been much worse, a computer expert at the University of Sheffield has claimed..
'Because this would be nowhere near the global spread and depth of attack if people had run the updates that Microsoft had provided in March'. By that time, Microsoft had discovered the bug on its own and issued a security update, but many users with older versions of Windows no longer receive such updates. It essentially relies on victims clicking on or downloading the attachment, which causes the program to run and infect your computer with ransomware.
For those running Windows 10 or Windows Vista, Windows 7 and Windows 8.1 systems, which has automatic updates turned on, you'll remain protected from WannaCry.
Telefónica: Spanish authorities confirmed the Spanish telecom company Telefónica was one of the targets, though the attack affected only some computers and did not compromise the security of clients' information.
Sadly, there isn't a simple formula for businesses to follow in regards to ransomware.
However, if you do pay, you're only fueling the fire.
Ms Rudd said the National Crime Agency (NCA) and the National Cyber Security Centre (NCSC) were now part of an "international manhunt" to find the perpetrators.
The only real security from ransomware is backups and solid security best practices.
Europol's European Cybercrime Centre said that anyone hit by ransomware should use the unlocking tools provided at NoMoreRansom.org, a free resource developed by Europol in partnership with the Dutch police and other industry partners.