One of the few surviving technological disciplines is nanotechnology. Some people argue that nanites are the only reason that humans survived the apocalypse… By 2160, nanotech was in use throughout the medical and industrial fields and most hospitals, laboratories, or factories worthy of the name had storerooms full of sealed jars of nanite strains. When the bombs started falling, forward-thinking survivors grabbed the more useful stores of nanite strains, and cultured them, sharing them between groups to the best of their ability. Doctors made sure that other medics had access to healing strains, craftsmen passed around strains that were designed to work metal. And the corporations got in on the act as well, gaining public recognition and influence by trading crucial strains to communities that lacked their own.
Most surviving nanites in the modern day are biological, and can reproduce given the right materials to feed upon. They’re kept in cool, dark places, and keep for decades as long as they’re fed a little biomass every now and then.
Thanks to nanotechnology, healing traumatic injuries is much easier, even within the space of seconds or minutes. Also, treating things like blood-borne toxins, and even radiation sickness, becomes possible. Many diseases remain untreatable, and birth defects like mutations are usually not affected by nanites, but short of that, modern medicine can truly work miracles.