This book is based on research carried out with nurses at two hospitals in Gabon. It looks at Covid-19 in emergency and intensive care nurses at Melen Hospital, on the one hand, and emergency nurses at Owendo University Hospital, on the other. The book has two aims: the first is to demonstrate factually that over-motivation at work influences the effects of the arduousness of nurses' work, and the second is to demonstrate from operational channels that motivation at work (intrinsic motivation, extrinsic motivation and amotivation) predicts risk-taking for Covid-19 contaminations. The aim here is to contribute to the literature on occupational contamination in the hospital environment, and to encourage the authorities to take a greater interest in issues relating to the arduousness of work and the risks of contamination in the hospital environment.