Normally, do not pick up calls from unknown callers.  However, when I read that this caller called 4x in a row, I decided to pick it up.  Caller said someone in my household had a medical condition, which is true.  He asked if we were in good health, and I said yes.  He went on to say he would like to ask a few questions to see if they could help.  I told him we were not interested, and hung up.