Dr. Daniel McCartney:

I will answer some of the Deputy questions in reverse order. Regarding the general recommendations, we would like a recommendation for 800 to 1,000 units for all adults in Ireland with the potential for higher doses in specifically vulnerable patients, that is, older people, people who are carrying extra weight or who are obese or overweight and people who have darker skin. There should also be direct provision of vitamin D supplementation to healthcare workers, the institutionalised elderly and our communities if possible, with nursing homes a priority.

The Deputy asked about countries that do things differently. There is a geographic difference in vitamin D status. We see it. Generally, vitamin D status is worse the further away one gets from the equator. There are exceptions, though. For example, in Italy and Spain we see much poorer vitamin D status than one would expect because people avoid the sun. They go in away from the sun during the daytime and their levels are lower for that reason. We also see much higher levels in some Scandinavian countries because their governments have been proactive in putting in place robust food fortification programmes and very well-communicated messaging on vitamin D supplementation, so they are getting it right. Finland's population has very good blood vitamin D levels and very low levels of infection and mortality from Covid-19. Norway and Sweden are also doing well on food fortification.

The Deputy asked about the prison population. I would absolutely put that population in among the vulnerable people who are much more likely to be vitamin D-deficient. The UK has said it will provide free vitamin D supplementation to the prison population there over the winter months this year.

I will hand over to Dr. Faul to respond to the Deputy's question about depression and seasonal affective disorder as they relate to vitamin D. I see Professor Kenny wants to come in on that as well. Perhaps Professor Kenny would go first, actually.