Chen Hao-yung of the NIPM says that once a virus develops into an urban virus it becomes very hard to eradicate. Viruses are very simple in structure, and as long as they have live cells to act as their hosts they can continue to reproduce. Hence cities, which have dense human populations and also harbor large numbers of rodents and other pests, are perfect breeding grounds for viruses.
預醫所病毒組組長陳豪勇指出，病毒一旦轉變成為都市型，就不容易被排除了，原因是病毒的構造簡單，只要有活的細胞作為宿主，就能繼續繁衍下去，而都市人口集中、鼠輩橫行，是病毒的最佳溫床。