Comparison of single versus booster dose of influenza vaccination on humoral and cellular immune responses in older adults

Abstract This study compared the immune response to the standard single-dose (SD) of influenza vaccine to a booster dose (BD) re-vaccination given 16 weeks after the initial dose. While seroprotection rates following vaccination were similar, T-cell responses were more optimally stimulated in the SD versus the BD group. SD lead to a greater than 10-fold decline in ex vivo interleukin-10 (IL-10) levels ( P P R  = .37–.50, P  ≤ .01) and ex vivo granzyme B (Grz B) levels ( R  = .50–.65, P  ≤ .001). Following vaccination, granzyme B levels were significantly higher in the SD compared to the BD group ( P  ≤ .0002). These results suggest that SD influenza vaccine produces Th1 and CTL responses while BD may produce a Th2 response that poorly stimulates the CTL response.