Researchers around the world are racing to develop a vaccine against Covid-19, with more than 170 candidate vaccines now in development. Most vaccines take years of testing and additional time to produce at scale, but scientists are hoping to develop a coronavirus vaccine at record speed. Several potential vaccines are now in the final phase of testing but it could still be months before we discover if they are safe and can effectively prevent people from being infected. If a vaccine can be found, there are concerns about how the world will manufacture enough. There may be challenges in storing it at the right temperature and transporting it safely around the world. Plus, rich countries might hoard supplies. Although hopes are high it is entirely possible that a safe and effective vaccine is a long way off, or never discovered. Experts warn that ‘waiting for a vaccine syndrome’ could be distracting us from finding other solutions for controlling the spread of Covid-19. Presenter: Tanya Beckett (A scientist works on an experimental coronavirus vaccine at a laboratory in Buenos Aires, Argentina. Credit: Juan Mabromata/Getty Images)