Amazing how certain people even now still believe that those who follow the measures in place to the letter and do everything to protect themselves should be immune to the virus, which of course only targets the reckless and irresponsible. If only it worked like that the last year would have been far less painful.
Also alot of misunderstanding over what the social bubbles and cohorts as used by Strictly and DoI respectively are. Strictly used bubbles which basically take advantage of the rule that allows any of us to bubble up with another household if you live alone - so by one or both partners living alone each pair could work within 2m of each other as they were in a bubble.
Close Contact Cohorts, as favoured by Dancing on Ice and ITV in general, are an industry arrangement where pairs or groups of people working together will be able to work within 2m of each other as long as they're not doing so with people outside of that cohort, with regular testing in place. Unlike Strictly I don't think it's required one part of the couple to be in a single household, but I think married pro-skaters are living separately for the show.
More info on that here:
https://www.itv.com/presscentre/sites/default/files/close_contact_cohorts.pdf
Neither Strictly or Dancing are using a "Covid-Free Bubble", which was the solution used for filming Bake Off and I'm a Celebrity,, plus the pro-dances for Strictly/DoI, where the show is filmed in a controlled environment with no contact from the outside world, so in theory once in the bubble everyone is safe.