The spread of infectious diseases from a physics perspective

Abstract This paper deals with the spread of infectious diseases from a physics perspective. It considers population as network nodes representing members, linked by edges (social) contacts individual members. Infections along these one node (member) to another. The presents novel, modified version SIR compartmental model, able account for typical effects and percolation phenomena. model is successfully tested against results simulations based on Monte-Carlo methods. Expressions (basic) reproduction numbers in terms parameters are presented, justify some mild criticisms widely interpretation being number secondary infections due single active infection. Throughout paper, special emphasis laid understanding, phenomena concepts borrowed condensed-matter statistical physics, which reveals interesting analogies. Percolation particular interest this respect they subject detailed investigation. concept herd immunity (its definition nature) intensively dealt well, also context large scale vaccination campaigns waning immunity. elucidates how onset herd-immunity can be considered 2nd-order phase transition play crucial role, thus corroborating, more pictorial/intuitive way, earlier viewpoints matter. An exact criterium most relevant form occur derived parameters. analyses presented provide insight various measures prevent an epidemic infection work, optimised what potentially deceptive issues have when such either implemented or scaled down.