Professor Sophie Harman, from Queen Mary University of London, joined BBC Radio 4 to discuss the response to Covid-19 from leaders across the world. Professor Harman said the issue with populism and Covid-19 is particularly interesting. She compared the big headline cases of the US and Brazil, where the co-operation with the WHO has been limited, to the dynamic in other populist countries, for example, within Europe. "It's a mixed bag in terms of the response. I think the serious concern is the potential domino effect of Trump's attitude to the WHO; if other populist leaders see what Trump's doing and follow suit." As the pandemic progresses, Professor Harman said that link between populism and a lack of co-operation could become more worrying. "Where this is going to really come to the fore and be problematic, is when it comes to a vaccine," with issues of who gets the vaccine first.