Chris Smith: Virologist on latest Covid-19 science

As New Zealand chafes under what could be last few days of its Level 4 lockdown, Dr Chris Smith returns to digest the week's scientific happenings. A consultant clinical virologist at Cambridge University, and one of BBC Radio 5 Live's Naked Scientists, he has the latest on the hunt for a vaccine, what we do and don't know about our immunity post infection, and the winding path to a fully functional antibody test to work out who's had the virus and who hasn't. Also on the agenda, the US decision to cut funding for the World Health Organisation, and how this could affect the battle not just against Covid-19, but also against diseases including polio in the developing world.