The science of social distancing

The strong social distancing policies introduced by China seem to have been successful in stopping the spread of Covid 19. Without any effective drug treatments, reducing our number of contacts is the most effective way to prevent viral transmission.We also look at the similarities been policies in Russia and the US on how best to deal with the virus. In both cases there are contradictions and disagreements between medical professionals and politicians. And a warning from Polio, how vaccines may create problems when immunisation campaigns do not reach everyone. (Image: Getty Images)Presenter: Roland Pease Producer: Julian Siddle