Insurance is vital and if she is going on a J1 ,I thought it was obligatory. Its not enough to rely on VHI insurance. To be honest I'd be so fussy about this that I wouldn't leave it up to her. I wouldn't be at all happy with her travelling there without seeing the documentation. My son paid a lot for his insurance with his J1 but at least one knew one wouldn't lose one's house if he was ill or injured. Also check re things like paragliding and bungee jumping , a lot of these activities will exclude insurance cover for subsequent injuries. About five years ago a friend of mine got sick in the US and had to have a cardiac procedure done. He was in hospital about five days. Bill 60,000 US dollars. Was he glad to have health insurance.
At the end of the day you will end up paying for her if she is not insured..
Hope she has a lovely time.