Less than a year in, and the first vaccines are already being rolled out, with many more in the pipeline. It is an unprecedented scientific response to the global pandemic and researchers around the world have provided the first hope against one of the most formidable challenges facing humanity in a century. Claudia Hammond and her expert panel of guests consider the scale of this herculean effort and answer listeners' questions about vaccine safety, trust, immunity, and long term protection. The World Health Organisation has repeatedly said that no-one is safe until we are all safe, so the threat of vaccine nationalism and the purchase of millions of the first vaccine doses by rich countries is something that is concerning everybody worried about equitable vaccine distribution. How will the COVAX facility, which is designed to boost vaccine purchasing power for the world's poorest countries, fare in the face of nationalistic purchasing - and will surplus doses be shared so that all seven point five billion of us can get protection? And, finally, the scale of the threat from vaccine hesitancy. Any vaccine is only as good as the number of people who will take it to achieve herd immunity. The numbers of those suspicious about a potential Covid-19 vaccine have grown over the course of the pandemic, causing real concern for governments around the world. How can people be reassured that vaccines are safe? This month, Claudia's guests include Professor Peter Hotez, Dean of the National School of Tropical Medicine at Baylor College of Medicine in Houston and co-director of the Texas Children's Hospital Centre for Vaccine Development in the USA, Professor Helen Rees, founder and executive director of the Wits Reproductive Health and HIV Institute, the University of Witwatersrand in South Africa, Kalipso Chalkidou, Professor of Practice in Global Health at Imperial College, London and Director of Global Health Policy at the Centre for Global Development and Dr Ève Dubé, a medical anthropologist from the Institute of Public Health in Quebec, Canada. Produced by: Fiona Hill, Samara Linton and Maria Simons Editor: Deborah Cohen Technical Support: Tim Heffer and Giles Aspen Picture: Covid-19 Vaccination Clinics Open In Surrey, UK, Credit: Leon Neal/Getty Images