The Delta variant of Covid-19 has raised concerns across the world, including in both the Republic and Northern Ireland.In particular, those who are not fully vaccinated have been warned to be careful by Chief Medical Officers on both sides of the border.But, just how concerned should we be?Kingston Mills, Professor of Experimental Immunology, School of Biochemistry and Immunology, Trinity College Dublin joined us to explain.Listen and subscribe to Newstalk Breakfast Weekends on Apple Podcasts, Google Podcasts and Spotify.Download, listen and subscribe on the Newstalk App.You can also listen to Newstalk live on newstalk.com or on Alexa, by adding the Newstalk skill and asking: 'Alexa, play Newstalk'.