Obesity-induced chronic inflammation is associated with the reduced efficacy of influenza vaccine.

The relationship between obesity and vaccine efficacy is a serious issue. Previous studies have shown that vaccine efficacy is lower in the obese than in the non-obese. Here, we examined the influence of obesity on the efficacy of influenza vaccination using high fat diet (HFD) and regular fat diet (RFD) mice that were immunized with 2 types of influenza virus vaccines-cell culture-based vaccines and egg-based vaccines. HFD mice showed lower levels of neutralizing antibody titers as compared with RFD mice. Moreover, HFD mice showed high levels of MCP-1 in serum and adipocytes, and low level of influenza virus-specific effector memory CD8(+) T cells. After challenge with influenza virus, the lungs of HFD mice showed more severe inflammatory responses as compared with the lungs of RFD mice, even after vaccination. Taken together, our data suggested that the inflammatory condition in obesity may contribute to the suppressed efficacy of influenza vaccination.