“…Salivary IgA is generally considered as an
immunity or stress marker, because saliva can be easily collected, noninvasively with little
stress. Many studies have demonstrated that salivary IgA concentrations decline with intensive
exercise, psychological stress, or aging [2,3,4,5,6,7,8,9,10,11,12,13,14,15]. Moreover, a correlation has been reported between the
decline in salivary IgA and the incidence of upper respiratory tract infection (URTI) [16,17,18,19,20,21,22,23,24].…”