I inquired about this at a Kaiser Pharmacy yesterday ~ and they know nothing about it, except that many others have made the same inquiry.  It is a SCAM CALL.  What is scary is how they at least think they 'know' that someone is a Kaiser member.

OK, my cell provider finally let me get a voicemail several hours after it was left. This is not a scam or telemarketing number. The number is an outreach number used by a branch of the Kaiser Permanente HMO.

Yup, called again a week later. No message. Now blocked.

Called my cell phone in the 949 AC. I let it go to answer but no message was left. I will assume on this one occasion only that this was a misdial. But if the number shows up in my call log one more time without a serious message or apology, it's a fast trip to Call Block City for whoever is doing this.