Whilst we’ve been celebrating the rollout of the covid-19 vaccines, new variants of the virus have thrown a spanner in the works, and there’s a concern over the lack of vaccine availability in low-income countries. The team explores these issues and highlights the exciting developments of both a nasal vaccine and (maybe) one which can be taken in pill form. Plus... Harvard astrophysicist Avi Loeb explains why he believes the interstellar object ‘Oumuamua could be a piece of alien technology, and tells us why scientists need to take the search for intelligent life more seriously. The team also finds out whether it’s ever ethical or sustainable to eat fish, they share the musical tones of an 18,000-year-old conch, and in a new segment which answers children’s ‘but why?’ questions, they tackle “what’s behind the sky?”. On the pod are Rowan Hooper, Tiffany O’Callaghan, Graham Lawton, Caroline Williams, and Leah Crane. To read more about the stories, subscribe at newscientist.com/podcasts.