From higher proportions of Covid-19 in urban areas being in line with expectations, to comments on Vitamin D, here are six things we learned at this evening's Covid-19 briefing.

Community effort is the most essential measure

Responding to a suggestion that the primary "lever" by which public health officials are trying to control Covid-19 is the community, Deputy Chief Medical Officer Dr Ronan Glynn said "that is absolutely the case" and said it is the same the world over.

He said that if the public do not go along with the measures officials implement then nothing will work.

Retrospective contact tracing

Dr Glynn said that NPHET would like to see retrospective contact tracing, and has been calling for it since August.

However, the Deputy CMO added that the health service has limited resources, and public health workers are struggling to keep up with current contact tracing.

Vitamin D

Dr Glynn said that many people In Ireland, do not get enough Vitamin D, and every person over 65 in the country should be taking a supplement.

However, he said there is no robust evidence at the moment that Vitamin D has an effect on preventing people becoming seriously ill with Covid-19.

"We have to be very careful about what we recommend to people to put into their bodies or the reasons that people put something into their bodies," Dr Glynn said.

He said he recommends Vitamin D as a generally positive thing people can do, but that that is different from saying it will prevent people from ending up in hospital with Covid-19.

AstraZeneca vaccine and older people

HSE Chief Clinical Officer Dr Colm Henry said that older people have had a "horrendous" experience with Covid-19, and the relative risk for older people is so much higher.

He said you use the most effective vaccines for the people who are at higher risk.

Dr Henry said it may well be that the real-world evidence shows higher efficacy for the AstraZeneca virus in older people than has been proven to date, but that we must make decisions on the evidence we have now rather than what we might expect to happen later.

Higher rates in Dublin

With Dublin accounting for close to half of the latest cases, concerns have been expressed about the rate of infection in the capital.

However, Prof Philip Nolan noted that it is not only Dublin that is affected, with other urban areas also showing higher proportions of cases compared to the national average.

He said that is to be expected as the level of the disease recedes across the country as a whole.

When cases were very low during the summer, Dublin also accounted for close to half the national case count.

Concern over plateauing in metrics despite improvements

Prof Nolan also noted that while the situation is improving, the rate at which cases and hospitalisations are falling has decreased.

He said this could be attributed to the B117 variant of Covid-19, which is more transmissible, and that we are now having to work even harder than ever to achieve the same levels of suppression of the disease.