Symptoms, Infection Duration, and Hemagglutinin Inhibition Antibody Response in Influenza A Infections.

Tricoche, Alexandria D; Wagner, Abram L; Balmaseda, Angel; Sanchez, Nery; Patel, Mayuri; Lopez, Roger; Schiller, Amy; Ojeda, Sergio et al. · J Infect Dis · 2021

retrospective_cohort · Level III

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Abstract

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% confidence interval, 1.02-4.64). Studies relying on serological assays may not generalize to asymptomatic infections.

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