Journal Article

Risk Factors and Attack Rates of Seasonal Influenza Infection

McArthur, Colin, Duque, Jazmin, Baker, Michael G., Collis, Emma, Roberts, Sally, Ralston, Jacqui, Retter, Amanda, McArdle, Barbara, Seeds, Ruth, Gross, Diane, Taylor, Susan, Wood, Tim, Huang, Q. Sue, Turner, Nikki, Jelley, Lauren, Lawrence, Shirley, Newbern, E. Claire, Bissielo, Ange, Metz, Thomas, Gunn, Wendy, Haubrock, Jennifer, Thompson, Mark G., Bandaranayake, Don, Mackereth, Graham, Wong, Conroy, Waite, Ben, Prasad, Namrata, Cameron, John, Thomas, Paul, Todd, Angela, McNicholas, Anne, Bocacao, Judy, Reynolds, Edwin G., Grant, Cameron C., Webby, Richard, Widdowson, Marc-Alain, Trenholme, Adrian, Wong, Sook-san

2019

Overview

Abstract Background Understanding the attack rate of influenza infection and the proportion who become ill by risk group is key to implementing prevention measures. While population-based studies of antihemagglutinin antibody responses have been described previously, studies examining both antihemagglutinin and antineuraminidase antibodies are lacking. Methods In 2015, we conducted a seroepidemiologic cohort study of individuals randomly selected from a population in New Zealand. We tested paired sera for hemagglutination inhibition (HAI) or neuraminidase inhibition (NAI) titers for seroconversion. We followed participants weekly and performed influenza polymerase chain reaction (PCR) for those reporting influenza-like illness (ILI). Results Influenza infection (either HAI or NAI seroconversion) was found in 321 (35% [95% confidence interval, 32%–38%]) of 911 unvaccinated participants, of whom 100 (31%) seroconverted to NAI alone. Young children and Pacific peoples experienced the highest influenza infection attack rates, but overall only a quarter of all infected reported influenza PCR–confirmed ILI, and one-quarter of these sought medical attention. Seroconversion to NAI alone was higher among children aged <5 years vs those aged ≥5 years (14% vs 4%; P < .001) and among those with influenza B vs A(H3N2) virus infections (7% vs 0.3%; P < .001). Conclusions Measurement of antineuraminidase antibodies in addition to antihemagglutinin antibodies may be important in capturing the true influenza infection rates. New Zealand’s seroepidemiological cohort study found that neuraminidase inhibition assay identified more influenza virus infections than hemagglutination inhibition assay. This result highlights the importance to measure serologically defined infections against not just hemagglutinin but also neuraminidase antigens in future seroepidemiologic cohort studies.

• Publisher: Oxford University Press
• Subject: Adolescent / Adult / Aged / Antibodies / Antibody Formation - immunology / Child / Child, Preschool / Children / Cohort analysis / Cohort Studies / Exo-a-sialidase / Female / Hemagglutination inhibition / Hemagglutination Inhibition Tests / Humans / Infant / Infant, Newborn / Infections / Influenza / Influenza A Virus, H3N2 Subtype - immunology / Influenza B / Influenza Vaccines - immunology / Influenza, Human - epidemiology / Influenza, Human - immunology / Influenza, Human - prevention & control / Male / Middle Aged / Neuraminidase - immunology / New Zealand - epidemiology / Polymerase chain reaction / Population studies / Risk Factors / Seasons / Seroconversion / Seroepidemiologic Studies / Vaccine efficacy / VIRUSES / Young Adult