What health insurance requirements are in place for the Non-Immigrant Category 'O-A' long stay visa application from the USA?

I've just been looking into the Non-Immigrant Category 'O-A' long stay visas for some American friends.

As I've heard the talk about Heath insurance... I just wanted to check if any systems are in place for that yet ... when making an application from the USA.

There is no mention of it online.

I just want to double check before I talk to them.

Can anyone give me any advise on this?

(Sorry, I can't seem to find a search function on my phone... so I'm hoping someone can pop up a quick update)

TIA 🙏🏼