It is four years since we reported the first cases of an outbreak of a mysterious viral pneumonia in the city of Wuhan in China. Within months, what become known as Covid-19, had spread around the world affecting most people in some way. The disease led to the creation of this programme. Since March 2020 – shortly after the World Health Organisation declared a pandemic – we began our first conversations. Four years on, we thought we would take the opportunity to return to Covid-19 and reunite some of the people we have spoken with over the past four years. Our conversations feature three doctors – in India, Italy and the US – who treated Covid-19 patients in the early days of the pandemic. Host James Reynolds also catches up with three former guests who have long Covid.