[Solved] When the world went to a system of floating exchange rates, the Balance of Payments became a relic of a system of fixed exchange rates and is no longer watched by serious economic groups. Vaccinated: The state of having received a vaccine, which induces an immune response to protect against specific diseases. Influenza: Influenza is a highly contagious viral infection that affects the respiratory system, causing seasonal epidemics and occasional pandemics. Viral Passage: The process by which a virus is grown in cells or organisms over multiple generations, leading to potential changes in its virulence or transmissibility. Morphological Features: Traits or attributes of an organism's form and structure, including shape, size, and arrangement of parts, visible under a microscope or with the naked eye.