I'm afraid I have no citation to offer, as I only know this second-hand.
For what it's worth: A friend of mine works as a doctor at a hospital in Fredrikstad, Norway, and she is the one who told me that this disease caused an unusual high rate of serious illness in otherwise healthy people. She also said that she confirmed this unusual pattern at her hospital.
But even this is a little bit beside my point: It's precisely that "little bit more risk", conferred on a demographic which is just not used to dealing with this stuff, that has been the main cause of the widespread panic. Whether that "little bit more risk" has resulted in them leading the death-rate statistics or not, is not really the issue.