Can improving the technologies of vaccination lead to gains in the capacity of the age-damaged immune system? Progress in the ability to manipulate the immune system may pay off in unexpected ways when further technologies are built atop a new platform: "Vaccine scientists say their 'Holy Grail' is to stimulate immunity that lasts for a lifetime. Live viral vaccines such as the smallpox or yellow fever vaccines provide immune protection that lasts several decades, but despite their success, scientists have remained in the dark as to how they induce such long lasting immunity. Scientists [have] designed tiny nanoparticles that resemble viruses in size and immunological composition and that induce lifelong immunity in mice. They designed the particles to mimic the immune‑stimulating effects of one of the most successful vaccines ever developed - the yellow fever vaccine. The particles, made of biodegradable polymers, have components that activate two different parts of the innate immune system and can be used interchangeably with material from many different bacteria or viruses. ... the yellow fever vaccine stimulated multiple Toll‑like receptors (TLRs) in the innate immune system. TLRs [are] molecules expressed by cells that can sense bits of viruses, bacteria and parasites ... the immune system sensed the yellow fever vaccine via multiple TLRs, and that this was required for the immunity induced by the vaccine. ... We found that to get the best immune response, you need to hit more than one kind of Toll‑like receptor. Our aim was to create a synthetic particle that accomplishes this task. ... In experiments with monkeys, nanoparticles with viral protein could induce robust responses greater than five times the response induced by a dose of the same viral protein given by itself, without the nanoparticles."