Abstract Background Many influenza studies assume that symptomatic and asymptomatic cases have equivalent antibody responses. Methods 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. Results 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% confidence interval, 1.02–4.64). Conclusions Studies relying on serological assays may not generalize to asymptomatic infections. Longer duration of influenza virus shedding and a stronger symptomatic response were associated with greater serological response to influenza among cases in Managua, Nicaragua.
【저자키워드】 antibodies, influenza A virus, Signs and symptoms, infectious disease transmission, hemagglutination inhibition tests,