Do I need Private Health Insurance for Stamp 4 Application

Hi there, could anyone advise me,myself and my wife are Irish citizens and recently we brought over my Thai wife's 2 children aged 14 and 17, I was advised by the immigration officer to apply for a stamp 4 for the 17 year old, what I need to know is do I need to have private health insurance for him for the application or not.I cannot seem to find this answer anywhere.Thanks

No you don't need private medical insurance for either of them. If the 17 year old entered on a d visa then get him an appointment for registration. If on c visa send an application to ISD.