The global burden of pediatric severe respiratory illness is substantial, and influenza viruses
contribute to this burden. Systematic surveillance and testing for influenza among hospitalized
children has expanded globally over the past decade. However, only a fraction of the
data has been used to estimate influenza burden. In this analysis, we use surveillance data
to provide an estimate of influenza-associated hospitalizations among children worldwide.
METHODS AND FINDINGS
We aggregated data from a systematic review (n = 108) and surveillance platforms (n = 37)
to calculate a pooled estimate of the proportion of samples collected from children hospitalized
with respiratory illnesses and positive for influenza by age group (<6 mo, <1 y, <2 y, <5
y, 5–17 y, and <18 y). We applied this proportion to global estimates of acute lower respiratory
infection hospitalizations among children aged <1 y and <5 y, to obtain the number and
per capita rate of influenza-associated hospitalizations by geographic region and socio-economic
Influenza was associated with 10% (95% CI 8%–11%) of respiratory hospitalizations in
children <18 y worldwide, ranging from 5% (95% CI 3%–7%) among children <6 mo to 16%
(95% CI 14%–20%) among children 5–17 y. On average, we estimated that influenza
results in approximately 374,000 (95% CI 264,000 to 539,000) hospitalizations in children
<1 y—of which 228,000 (95% CI 150,000 to 344,000) occur in children <6mo—and
870,000 (95% CI 610,000 to 1,237,000) hospitalizations in children <5 y annually. Influenza-
associated hospitalization rates were more than three times higher in developing countries than in industrialized countries (150/100,000 children/year versus 48/100,000).
However, differences in hospitalization practices between settings are an important limitation
in interpreting these findings.
Influenza is an important contributor to respiratory hospitalizations among young children
worldwide. Increasing influenza vaccination coverage among young children and pregnant
women could reduce this burden and protect infants <6 mo.
S1 Appendix. Summary of published articles included in the analyses, with reference list.
S2 Appendix. Summary of influenza-associated ALRI and total number of influenza-associated
hospitalizations in children 0–5 mo and 6–11 mo, with reference list.
S1 Data. Analysis dataset.
S1 Fig. Forest plot of data sources with PCR testing for pooled estimate, children <6 mo.
S2 Fig. Forest plot of data sources with PCR testing for pooled estimate, children <1 y.
S3 Fig. Forest plot of data sources with PCR testing for pooled estimate, children <2 y.
S4 Fig. Forest plot of data sources with PCR testing for pooled estimate, children <5 y.
S5 Fig. Forest plot of data sources with PCR testing for pooled estimate, children <18 y.
S6 Fig. Forest plot of data sources with PCR testing for pooled estimate, children 5–17 y.
S1 PRISMA checklist.
S1 Table. Literature search methodology and results, by database.