Vaccination pathways are important in inducing efficient immune responses, and different immunization routes may elicit different immune responses to the same protein antigens. For example, immunization of mice with a MERS-CoV subunit vaccine (RBD-Fc) via the intranasal route induced higher levels of cellular immune responses and stronger local mucosal neutralizing antibody responses against MERS-CoV infection than those induced by the same vaccine via the S.C. pathway (Ma et al., 2014a). In addition, while Freund’s and CpG-adjuvanted rRBD protein elicited higher-level systematic and local IFN-γ-producing T cells via the S.C. route, this protein adjuvanted with Alum and CpG induced higher-level tumor necrosis factor-alpha (TNF-α) and interleukin 4 (IL-4)-secreting T cells via the I.M. route (Lan et al., 2014).