The Covid-19 pandemic is the most significant health emergency of our time. Writing from Italy in lockdown, physicist and novelist Paolo Giordano explains how disease spreads in our interconnected world: why it matters how it impacts us how we must react Expanding his focus to include other forms of contagion - from the environmental crisis to fake news and xenophobia - Giordano shows us not just how the coronavirus crisis got so bad so quickly, but also how we can work together to create change. Paolo Giordano is a physicist and the author of four bestselling novels. His article 'The Mathematics of Contagion' - published in Italy at the beginning of the coronavirus emergency - was shared more than 4 million times and helped shift public opinion in the early stages of the epidemic.