More than 800 people are in hospital with Covid-19 for the first time since April.

As of 8am, there were 812 patients with the virus in hospital - up 14 on the same time yesterday.

Of these, 32 patients are in intensive care units with Covid-19, which is down one since yesterday.

It comes as an immunologist has warned that there are many people being infected with Covid-19 without realising it as they are asymptomatic.

Professor Cliona O'Farrelly said there are currently "huge amounts" of Covid in the community.

Speaking on RTÉ's Today with Claire Byrne, Prof O'Farrelly said that people who have not yet been infected with the virus may have innate immune systems that are effective at keeping it away, but also there are many others who have been careful and managed to avoid contracting it.

She said a Trinity College Dublin study is trying to distinguish between the two categories as it explores who might have a natural immune system against Covid-19.

She said the international study is focused on people who did not get the virus at all but were exposed to it before they were vaccinated.

Prof O'Farrelly said 16,500 people have signed up to take part in the study and researchers are looking specifically for people who were living with someone who has been infected, but still did not get the virus.

She said that as many people have been vaccinated now it harder to determine whether this is the reason that they have not been infected or whether it is their natural immunity.

Meanwhile, Dr Tony Holohan is stepping down as Chief Medical Officer today after 14 years in the role.

Dr Holohan announced his resignation in March.

Professor Breda Smyth will take up the role of Interim CMO from Monday.

Prof Smyth has specialised in public health for the last 16 years and is currently Professor for Public Health Medicine in NUI Galway and Consultant in Public Health in HSE West.