I am pretty certain that if you do not renew the book you will not receive any IKA treatment until it is renewed.
Not necessarily so. My two penn'orth for what it's worth.
As I mentioned elsewhere, I am engaged in a long-running battle with the social security system, one front of which is the refusal of IKA to renew my vivliario. It expired at the beginning of last year. Efka, the umbrella organisation with which I am now insured* can't intervene because it's IKA who actually issue the book. But they assured me that the lack of book would not prevent me from using the Greek health system. "Just give your AMKA number. That's all you need".
Since getting that assurance I have successfully used "just the AMKA number" - once to to get Xrays and medication from the local health centre, once very recently for a consultation with an orthopedic specialist at the Panepistimiako.
He is proposing to give me a new knee towards the end of this year, and I am perhaps understandably reluctant to test out the "just use AMKA" plan for an op costing thousands of quid, in case I end up having to pay.
So I am pursuing the vivliario, at some expense in money and time, because it's the one and only benefit I expect or need from my membership of EFKA and because the cop shop were insisting on seeing it in order to give me a new residence document for the one I've lost.
*That's all I have to say which is immediately on topic, but just in case anyone's still with me, I'll add the latest jolly development. Kostas at the astinomia said "they" might accept a paper from KEP saying that I'm insured. Kostas at KEP said he'd happily oblige, but when he input my code into the EFKA site, it says I am "not insured". Funny, that. I paid EFKA 2000 euros for insurance last year.
**I say "document" because although it was issued in 2006 and I've never used it for anything, ever, which is how it came to get lost, I know that it was blue. So was it a permit, a certificate or a diploma (Grade 1) in Greek bureaucracy? What colour/manner of document will the replacement be? But I forgot. I can't get a replacement until I get a vivliario. There's a very big hole in my bucket.