A vaccine is a substance that protects humans or animals from infectious and non-infectious diseases after intake into the body. In the modern period, vaccine development was successful to protect against several infectious diseases such as smallpox, rabies, poliomyelitis, and measles, although we are facing difficulty in developing an efficacious human immunodeficiency virus vaccine. We still have difficulty obtaining long-term protective effects by a vaccine against seasonal influenza viruses due to their continuous antigenic changes. More recently, novel coronavirus disease caused by a severe acute respiratory syndrome virus type 2 (SARS-CoV-2) emerged in 2019, and an mRNA-based vaccine was developed that showed certain protective effects against SARS-CoV-2 diseases. In this chapter, I provide outlines of novel vaccine development, factors affecting acceptance of novel vaccines in several populations, and efforts towards development of vaccines acceptable for all populations regardless of ethnicity and religion.