Many influenza studies assume that symptomatic and asymptomatic cases have equivalent antibody responses. This study examines the relationship between influenza symptoms and serological response. Influenza-positive index cases and household members in Managua, Nicaragua, during 2012-2017 were categorized by symptom status. Antibody response was assessed using Hemagglutination Inhibition Assays (HAI). Among 510 cases, 74.5% had ≥4-fold increase in HAI antibodies, and 75.3% had febrile illness. In a logistic regression model, febrile cases had 2.17 times higher odds of a ≥4-fold titer rise compared to asymptomatic cases (95% CI: 1.02, 4.64). Studies relying on serological assays may not generalize to asymptomatic infections.