New research reveals a poor immunity boost after infection with the Omicron variant. Might this explain why getting Covid again has been more common with this wave? BBC News health reporter, Smitha Mundasad unpicks the data. And the first World Health Organisation mental health report in two decades calls for change. Dévora Kestel, Director of WHO’s Mental Health and Substance Use Department joins Claudia Hammond to discuss the findings. Plus Professor Russell Foster on why looking after our body clocks can help with a good night's sleep. Presenter: Claudia Hammond Producer: Erika Wright (Picture: Covid-19 Omicron illustration. Photo credit: Sakchai Vongsasiripat/Getty Images.)