Pre and post influenza vaccination HAI (g, h, i) and MN (j,k) titers in participants with confirmed influenza (open circles) and matched uninfected controls (black circles)

Pre and post influenza vaccination HAI (g, h, i) and MN (j,k) titers in participants with confirmed influenza (open circles) and matched uninfected controls (black circles). Recruitment criteria for this study were adults 18 years of age and older receiving the seasonal trivalent inactivated influenza vaccine Valsartan (IIV3) for the years 2013C2014 and 2014C2015. Exclusion criteria were immunosuppressive diseases, use of immunomodulatory or immunosuppressive drugs, acute febrile illness, history of Guillain-Barre syndrome, use of theophylline preparations, or use of warfarin. Results Among obese, 9.8% had either confirmed influenza or influenza-like-illness compared with Valsartan 5.1% of healthy weight participants. Compared with vaccinated healthy weight, obese participants had double the risk of developing influenza or influenza-like illness (relative risk= 2.01, 95% CI 1.12, 3.60, p=0.020). Seroconversion or seroprotection rates were not different between healthy weight and obese adults with influenza or ILI. Conclusions Despite robust serological responses, vaccinated obese adults are twice as likely to develop influenza and influenza-like illness compared to healthy weight adults. This finding challenges the current standard for correlates of protection, suggesting use of antibody titers to determine vaccine effectiveness in an obese population may provide misleading information. INTRODUCTION Influenza is a serious worldwide public health problem. Seasonally, 5C10% of adults and 20C30% of children contract influenza virus, resulting in up to 500, 000 deaths1 and influenza pandemics greatly increase the number of infections and deaths. Indeed, the 1918 influenza pandemic was estimated to have infected 20C40% of the worlds population, causing approximately 50 million deaths2. Historically, the highest risk groups for increased morbidity and mortality from influenza infection include the elderly3, the very young4, individuals with chronic diseases such as diabetes5 or congestive heart failure6, and pregnant women7. During the 2009 H1N1 pandemic, obesity was recognized as an independent risk factor for complications from influenza8 and continues to be a risk factor for seasonal influenza Rabbit polyclonal to ETFDH strains9 as well as for emerging influenza virus strains such as A(H7N9)(ref. 10). Obesity is not only a concern in the US, with 37% of adults obese11, but also affects 14% of the worldwide adult population12. Therefore, with a growing obesity epidemic, complications from influenza infection would be expected to increase. Influenza vaccine remains the primary method currently available for prevention of influenza infection. Each year, vaccines are formulated based on evaluations of previously circulating influenza strains. Typically, the vaccine contains two influenza A strains and one, or more recently two, influenza B Valsartan strains. Vaccine-generated antibodies against the viral surface protein hemagglutinin (HA) are considered to be protective, therefore vaccines are standardized to the quantity of HA, generally 15 g of HA per strain13. A serum hemagglutination inhibition (HAI) titer of 40 or greater has historically been considered an immunological correlate of protection from influenza infection, corresponding to 50% protection14. Protection against influenza infection increases up to an HAI titer of 160, beyond which further protective capacity is minimal15. High risk groups for influenza infection, including the elderly and children under 6 years of age, may need to reach titers greater than 40 to achieve protection16. To determine if obesity altered the risk of developing influenza or ILI in a vaccinated adult population, we report the incidence of influenza infection and influenza-like illness (ILI) in vaccinated obese and healthy weight adults as well as the extent to which participants with influenza infection and ILI produced influenza specific antibodies. SUBJECTS AND METHODS Study Design Participants were recruited as a part of a prospective observational study carried out at the University of North Carolina at Chapel Hill Family Medicine Center, an academic outpatient primary care facility in Chapel Hill, North Carolina. All procedures were approved by the Biomedical Institutional Review Board at the University of North Carolina. At enrollment, informed written consent was received. Participants Recruitment criteria for this study were adults 18 years of age and older receiving the seasonal trivalent inactivated influenza vaccine (IIV3) for the years 2013C2014 and 2014C2015. Exclusion criteria were immunosuppressive diseases including HIV, use of immunomodulatory or immunosuppressive drugs, acute febrile illness, history of.