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The Spectrum of Influenza in Children
Gregory Hoy1, Guillermina Kuan2,3, Roger López2,4
1Department of Epidemiology, School of Public Health, University of Michigan, Ann Arbor, Michigan, USA.
Insights
Asymptomatic influenza infections are less common in children than adults, but viral shedding can still occur. Post-influenza complications are rare in pediatric populations, with virus strain influencing risk.
Area of Science:
- Pediatric infectious diseases
- Virology
- Epidemiology
Background:
- Influenza poses a significant burden on children, impacting community transmission.
- The prevalence of asymptomatic influenza infections and post-influenza complications in children remains poorly understood.
Purpose of the Study:
- To investigate the frequency of asymptomatic influenza infections in children.
- To determine the occurrence of post-influenza sequelae in pediatric populations.
- To explore the relationship between influenza virus strains and the risk of complications.
Main Methods:
- Utilized data from two community-based prospective cohort studies and one case-ascertained study in Managua, Nicaragua (2011-2020).
- Included non-immunocompromised children aged 0-14 years with confirmed influenza infections via polymerase chain reaction and hemagglutination inhibition assay.
Main Results:
- Asymptomatic influenza occurred in 6.6% of infections, increasing with age (1.7% to 9.1%).
- Viral shedding was observed in 51.2% of asymptomatic children versus 92.5% of symptomatic children.
- Post-influenza sequelae, such as pneumonia and acute otitis media, were rare (2.4% and 3.3%, respectively).
- Specific influenza strains (A/H1N1, B/Victoria) were associated with increased odds of certain complications.
Conclusions:
- Asymptomatic influenza is less frequent in children than adults, yet viral shedding persists.
- Post-influenza complications are uncommon in community-dwelling children.
- Influenza virus strain is a potential factor influencing the risk of developing sequelae.
Background:
Children constitute an important component of the influenza burden and community transmission, but the frequency of asymptomatic infection and post-influenza sequelae at the community level is poorly understood.
Methods:
Two community-based prospective cohort studies (2011-2020, 2017-2020) and 1 case-ascertained study (2012-2017) were conducted in Managua, Nicaragua. Non-immunocompromised children aged 0-14 years with ≥1 influenza infections, determined by polymerase chain reaction and hemagglutination inhibition assay, were included.
Results:
A total of 1272 influenza infections occurred in the household-based portion of the study. Influenza infection was asymptomatic in 84 (6.6%) infections, and the asymptomatic fraction increased with age (1.7%, 3.5%, and 9.1% for ages 0-1, 2-4, and 5-14, respectively; P < .001). Of asymptomatic children, 43 (51.2%) shed virus, compared to 1099 (92.5%) symptomatic children (P < .001). Also, 2140 cases of influenza occurred in the primary care portion of the study. Sequelae of influenza were rare, with the most common being pneumonia (52, 2.4%) and acute otitis media (71, 3.3%). A/H1N1 had higher age-adjusted odds of acute otitis media (odds ratio [OR] 1.99, 95% confidence interval [CI]: 1.14-3.48; P = .015) and hospitalization (OR 3.73, 95% CI: 1.68-8.67; P = .002) than A/H3N2. B/Victoria had higher age-adjusted odds of pneumonia (OR 10.99, 95% CI: 1.34-90.28; P = .026) than B/Yamagata.
Conclusions:
Asymptomatic influenza infection is much less common in children than adults, although viral shedding still occurs in asymptomatic children. Post-influenza sequelae are rare in children in the community setting, and virus strain may be important in understanding the risk of sequelae.
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