Increased risk of influenza among vaccinated adults who are obese

Abstract

Background Influenza infects 5–15% of the global population each year, and obesity has been shown to be an independent risk factor for increased influenza-related complications including hospitalization and death. However, the risk of developing influenza or ILI in a vaccinated obese adult population has not been addressed. Objective This study evaluated whether obesity was associated with increased risk of influenza and influenza-like illness among vaccinated adults. Subjects and Methods During the 2013–2014 and 2014–2015 influenza seasons, we recruited 1042 subjects to a prospective observational study of trivalent inactivated influenza vaccine (IIV3) in adults.1022 subjects completed the study. Assessments of relative risk for laboratory confirmed influenza and influenza-like illness were determined based on BMI. Seroconversion and seroprotection rates were determined using pre-vaccination and 26–35 days post-vaccination serum samples. Recruitment criteria for this study were adults 18 years of age and older receiving the seasonal trivalent inactivated influenza vaccine (IIV3) for the years 2013–2014 and 2014–2015. 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 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.

Obesity and ageing: Two sides of the same coin

“…Therefore, people with obesity are at higher risk for influenza and less protected by vaccination. Of particular note is that even when seroconversion or seroprotection rates are the same, compared with lean adults, vaccinated adults with obesity are still twice as likely to develop influenza and influenza‐like illness …”

Influenza in High-Risk Hosts—Lessons Learned from Animal Models

“…Seasonal vaccination remains the safest and most efficacious way to prevent influenza infection and reduce disease severity, although not all hosts respond adequately to these preventative measures (Kennedy et al 2012;Green and Beck 2017;Zerbo et al 2017;Dhakal and Klein 2019). Because of the altered immune system in obese models, it is not surprising that the influenza vaccine is less efficacious in obese individuals (Neidich et al 2017). Genetically obese mice vaccinated both with and without adjuvant were not protected against homologous viral challenge (Karlsson et al 2016).…”

Impact of Maternal BMI on Rubella Nonimmunity at Antenatal Screening

“…Obesity adversely affects lymphoid tissue integrity and leukocyte response as well as the coordination between innate and adaptive immune responses (). This could potentially explain the increased likelihood of poor vaccine‐induced immunity to the hepatitis B vaccine () and the twofold increased incidence of influenza‐like illness despite a robust serological response to influenza vaccination (). One postulated mechanism is that elevated tumor necrosis factor‐α production in subjects with obesity causes a reduction in T‐cell population subsets and their functions, which can be reversed by adequate weight reduction ().…”