It is an extension for the Iceland country TLD. Not every more popular registrars allows the ability to buy such domains. I used to have a keyword hack with it...that one did not really work out hehe
What I can tell is that the name has been previously registered to Samtök iðnaðarins which is the biggest employers organization in the country. I don't know when and why they dropped this name but it's not their core business. They already own a dozen .is domains according to data in my possession. Enough to cover their main fields of activity.
You could still contact the holder of the Icelandic counterpart heilsa.is but their focus is the domestic market.
Also a couple possible leads from old lists of mine - warning some of these names may have dropped by now: