No

A cyber attack is a cyber operation, whether offensive or defensive, that is reasonably expected to cause injury or death to persons or damage or destruction to objects.

Michael Schmitt et al; Tallinn Manual 1.0, pp 92
  • Cyber Operation?
  • Expected to cause death or injury to people or objects?
Irish Healthcare Ransomware Incident does not match this definition. Here's a list of actual cyberattacks and and why this matters.

What happened?

Ireland’s health service operator shut down all its IT systems to protect it from what it described as a significant ransomware attack but said its COVID-19 vaccination program was unaffected.