To some on the internet, the cheap anti-parasitic drug Ivermectin is a potential wonder drug that could dramatically change the global fight against Covid-19. It has passionate proponents, from a small group of scientists to the more conspiratorially-minded. But with a scattered evidence base of varying quality, what - if anything - do we know for sure about Ivermectin? And is uncovering the truth a more complex process than some appreciate? With Gideon Meyerowitz-Katz from the University of Wollongong, Australia. Producer: Nathan Gower