One important aspect: The AZ vaccine was in Norway (and many EU countries) initially only approved for those under 65. The AZ vaccine in Norway has therefore so

One important aspect: The AZ vaccine was in Norway (and many EU countries) initially only approved for those under 65. The AZ vaccine in Norway has therefore solely been given out to health workers. On the other hand, in the UK the vaccine has been given out to both elderly and to health workers. It is quite possible that the immune response from AZ is not quite the same across age groups and may at times be more severe for a younger population.