Association between obesity and vulnerability and serologic response to influenza vaccination in older adults

► Obesity was not associated with seroprotection to influenza vaccine in adults. ► Vulnerability was not associated with seroprotection against the 2008-2009 vaccine. ► We did observe increased seroconversion to the H3N2 subtype among obese subjects. ► Seroconversion to the H1N1 subtype was increased among more vulnerable subjects.