IL15 and respiratory syncytial virus infectious disease: The levels of IL-15 in peripheral blood or tissue have been shown to be increased in many viral infections, such as HIV (Leeansyah et al., 2013; Younes et al., 2016), HAV (Kim et al., 2018), simian immunodeficiency virus (Jacquelin et al., 2014), DENV (Azeredo et al., 2006), and respiratory syncytial virus infection (Estripeaut et al., 2008).