Verification of vaccine efficacy is necessary as it shows how well a candidate vaccine works in humans. However, testing vaccine efficacy in humans is costly, time-consuming, and complex because it may involve a large number of participants who might have geographic or demographic biases and it requires following cohorts of subjects for years to monitor protective efficacy. Moreover, vaccine efficacy studies in humans could get trouble in ethical issues when it comes to certain pathogens like HIV. Contrarily, model organisms, which are easy to maintain and breed in a laboratory setting with a short generation time, permit faster evaluation of promising vaccine candidates at a lower cost and risk compared with humans. Some model organisms have similar genes or similar-sized genomes to humans, which means they can mimic the pathophysiology of human disease after being infected by a target pathogen and bear a resemblance to human immune responses. Theoretically, the imm...