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. 2022 Feb 21;176(5):520–522. doi: 10.1001/jamapediatrics.2021.6566

Severity of Hospitalizations From SARS-CoV-2 vs Influenza and Respiratory Syncytial Virus Infection in Children Aged 5 to 11 Years in 11 US States

William Encinosa 1,, Jessica Figueroa 2, Youssef Elias 3
PMCID: PMC8861895  PMID: 35188536

Abstract

This cross-sectional study investigates the severity of hospitalizations from SARS-CoV-2 infection compared with that of influenza and respiratory syncytial virus in children aged 5 to 11 years in 11 US states.


In October 2021, the US Food and Drug Administration granted emergency use authorization for the BNT162b2 (Pfizer-BioNTech) COVID-19 vaccine to be used in children aged 5 to 11 years to reduce costly hospitalizations. By that time, for children in this age group, there had been 1.8 million people diagnosed with SARS-CoV-2 infection and 143 deaths, with more than 8000 hospitalizations.1 However, very little is known about the severity of these hospitalizations relative to the 2 most common childhood viruses, the influenza virus and respiratory syncytial virus (RSV), which resemble the SARS-CoV-2 virus. In this study, we compared the January through March 2021 hospitalizations of children aged 5 to 11 years who were diagnosed with SARS-CoV-2 infection and multisystem inflammatory syndrome in children (MIS-C; a sequela of COVID-19 disease)2 with those hospitalizations of children aged 5 to 11 years infected with influenza and RSV.

Methods

This cross-sectional study was conducted from September 17 to December 13, 2021, using 2021 quarterly inpatient data from the Healthcare Cost and Utilization Project of the Agency for Healthcare Research and Quality. These data were from the first 11 states with complete first-quarter data as of October 2021: Colorado, Georgia, Iowa, Kentucky, Michigan, Missouri, Mississippi, Ohio, New Jersey, Washington, and Wisconsin. Data from these states represented 24% of the US population of children aged 5 to 11 years.3 We examined all 1333 community hospitals in these states during the first quarter of 2021 (January to March) because the number of COVID-19–related diagnoses peaked in January. We used the International Statistical Classification of Diseases, Tenth Revision, Clinical Modification codes to identify COVID-19, MIS-C, influenza, and RSV. Because diagnoses of influenza and RSV were rare during the COVID-19 pandemic, we also used data from the first quarter of 2017 of the State Inpatient Databases, when influenza was at its mean 10-year level (2019 and 2020 had below average influenza rates, whereas 2018 rates were above average).4 We examined 46 complications in the following body systems: cardiovascular, respiratory, neurologic, hematologic, kidney failure, gastrointestinal, and musculoskeletal. Total costs and charges were adjusted for the US Centers for Medicare & Medicaid Services wage index and inflation adjusted to 2021. Race and ethnicity data were collected from the database; children were identified as Asian or Pacific Islander, Black, Hispanic, non-Hispanic White, or other (included Native American or other as reported by the Healthcare Cost and Utilization Project). Race and ethnicity data collection was a requirement of the funding body. This study was approved by the institutional review board of the Agency for Healthcare Research and Quality, and followed the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) reporting guidelines. The need for patient informed consent was waived owing to the use of deidentified patient data. The eMethods in the Supplement contains information on diagnostic codes and missing race imputations. All 2-sided P values were generated from linear regression analyses using Stata/MP, version 17 (StataCorp), and a P value < .05 was considered significant.

Results

This cross-sectional study included the patient data from a total of 2269 children (mean [SD] age, 7.6 [2.0] years; 999 girls [44.0%]; 1270 boys [56.0%]; 50 Asian or Pacific Islander [2.2%], 265 Black [11.7%], 539 Hispanic [23.8%], 1305 non-Hispanic White [57.5%], 110 other [4.8%]). In the Table, for every COVID-19 hospitalization, there was a corresponding MIS-C hospitalization. Combined, COVID-19 and MIS-C hospitalizations occurred at a rate of 10.8 per 100 000 children. Influenza and RSV were rare during the first quarter of 2021 (23 discharges combined), but in 2017, influenza and RSV had 17.0 and 6.2 hospitalizations per 100 000, respectively. A total of 56.8% (95% CI, 51.0%-62.7%) children who were Asian or Pacific Islander, Black, Hispanic, or other race and ethnicity had diagnoses of MIS-C compared with 28.4% (95% CI, 23.7%-33.1%) for RSV. Inpatient death for all viruses was rare. MIS-C had the highest rates of cardiovascular (29.8%; 95% CI, 25.2%-34.4%; P = .001), hematologic (55.4%; 95% CI, 50.4%-60.4%; P = .001), kidney (21.9%; 95% CI, 17.7%-26.1%; P = .001), and gastrointestinal (47.2%; 42.2%-52.3%; P = .001) complications. Children with RSV had the highest rate of respiratory complications (75.8%; 95% CI, 71.6%-79.9%; P = .001), whereas children with COVID-19 (without MIS-C) had the highest rate of neurologic complications (9.6%; 95% CI, 6.5%-12.8%; P = .03). Children with influenza had the highest rate of musculoskeletal complications (9.5%; 95% CI, 7.8%-11.2%; P = .001).5 Children with MIS-C had the longest median (IQR) length of stay (5 [3-7] days), at a median (IQR) cost of $23 585 ($15 040-$39 122) per stay, compared with children with a diagnosis of influenza (median [IQR]: length of stay, 2 [1-4] days; cost, $5200 [$2959-$9449]).

Table. Hospitalizations of Children Aged 5 to 11 Years by Viral Infection Across 11 Statesa.

Variable No. (95% CI)
January-March 2021 January-March 2017
MIS-C SARS-CoV-2 without MIS-C Influenza RSV
Total, No. 379 343 1134 413
Total, No. per 100 000 kids 5.7 5.1 17.0 6.2
Demographic characteristics
Age, median (IQR), y 8 (7-10) 8 (7-10) 7 (6-9)b 6 (5-8)b
Proportion of female children 0.406 (0.357-0.456) 0.458 (0.405-0.511) 0.415 (0.387-0.444) 0.525 (0.477-0.574)b
Proportion of male children 0.594 (0.544-0.643) 0.542 (0.489-0.595) 0.585 (0.556-0.613) 0.475 (0.426-0.523)b
Proportion of each race and ethnicity
Asian or Pacific Islander 0.029 (0.009-0.049) 0.015 (0-0.029) 0.026 (0.016-0.035) 0.011 (0-0.022)
Black 0.101 (0.065-0.136) 0.158 (0.114-0.202)e 0.105 (0.086-0.124) 0.129 (0.094-0.164)
Hispanic 0.381 (0.324-0.439) 0.239 (0.188-0.290)b 0.243 (0.216-0.270)b 0.090 (0.060-0.120)b
Non-Hispanic White 0.432 (0.373-0.490) 0.551 (0.492-0.611)b 0.579 (0.548-0.610)b 0.716 (0.669-0.763)b
Otherc 0.058 (0.030-0.085) 0.037 (0.014-0.059) 0.047 (0.034-0.060) 0.053 (0.030-0.077)
Outcomes
Inpatient death <11d <11d <11d <11d
No. of body systems affected 1.913 (1.775-2.050) 0.866 (0.763-0.969)b 0.981 (0.930-1.032)b 1.266 (1.185-1.348)b
Complications
Cardiovascular 0.298 (0.252-0.344) 0.032 (0.013-0.051)b 0.020 (0.012-0.028)b 0.029 (0.013-0.045)b
Myocarditis/pericarditis 0.111 (.079-.143) <11d <11d <11d
Respiratory 0.282 (0.237-0.328) 0.210 (0.167-0.253)e 0.306 (0.279-0.333) 0.758 (0.716-0.799)b
Neurologic 0.050 (0.028-0.072) 0.096 (0.065-0.128)e 0.063 (0.048-0.077) 0.063 (0.039-0.086)
Hematologic 0.554 (0.504-0.604) 0.134 (0.098-0.170)b 0.099 (0.081-0.116)b 0.126 (0.094-0.158)b
Sepsis 0.108 (0.077-0.140) 0.050 (0.026-0.073)b 0.034 (0.023-0.044)b 0.065 (0.041-0.089)b
Shock 0.142 (0.107-0.178) <11d 0.017 (0.009-0.024)b 0.031 (0.015-0.048)b
Kidney failure 0.219 (0.177-0.261) 0.067 (0.040-0.094)b 0.036 (0.025-0.047)b 0.034 (0.016-0.051)b
Gastrointestinal 0.472 (0.422-0.523) 0.312 (0.263-0.361)b 0.364 (0.336-0.392)b 0.252 (0.210-0.294)b
Musculoskeletal 0.037 (0.018-0.056) <11d 0.095 (0.078-0.112)b <11d
Utilization, median (IQR), No.
Length of stay, d 5 (3-7) 3 (2-6)b 2 (1-4)b 3 (2-6)b
Hospital costs, $ 23 585 (15 040-39 122) 10 399 (5314-23 546)b 5200 (2959-9449)b 9080 (4648-21 075)b
Hospital charges, $ 78 208 (52 896-114 562) 34 946 (20 231-73 689)b 17 696 (10 579-31 032)b 29 166 (15 335-63 780)b

Abbreviations: MIS-C, multisystem inflammatory syndrome for children; RSV, respiratory syncytial virus.

a

Includes data from the first quarter of 2021 (January-March) from 1333 hospitals in Colorado, Georgia, Iowa, Kentucky, Michigan, Missouri, Mississippi, New Jersey, Ohio, Washington, and Wisconsin. Complications are defined in the eMethods in the Supplement.

b

Significantly different compared with MIS-C: P < .01.

c

Other includes Native American or other as reported by the Healthcare Cost and Utilization Project.

d

Values masked owing to a patient number less than 11.

e

Significantly different compared with MIS-C: P < .05.

MIS-C was more severe for children who were Asian or Pacific Islander, Black, Hispanic, and other race and ethnicity. In the Figure, aggregate inpatient days for children who were Asian or Pacific Islander, Black, Hispanic, and other race and ethnicity with MIS-C was almost twice that of non-Hispanic White children (1647 days vs 867 days; P = .047), despite children who were Asian or Pacific Islander, Black, Hispanic, and other race and ethnicity accounting for only 56.8% of the cases. Non-Hispanic White children accounted for more total days for SARS-CoV-2, influenza, and RSV infection than children who were Asian or Pacific Islander, Black, Hispanic, and other race and ethnicity (combined, 5174 days vs 3197 days; P = .01). Children were hospitalized for approximately the same number of days for COVID-19 infection and MIS-C combined as for influenza (4384 days vs 4202 days; P = .65), despite having a lower hospitalization rate (10.8 per 100 000 children vs 17.0 per 100 000 children).

Figure. Total Cumulative Inpatient Days Across 11 States for Children Aged 5 to 11 Years, by Disease and Race.

Figure.

The figure includes data of all children admitted to the hospital for the following infections: influenza, respiratory syncytial virus (RSV), SARS-CoV-2 COVID-19 (without multisystem inflammatory syndrome in children [MIS-C]), and MIS-C. These data were acquired across 11 states: Colorado, Georgia, Iowa, Kentucky, Michigan, Missouri, Mississippi, New Jersey, Ohio, Washington, and Wisconsin.

aOther includes Native American, Pacific Islander, or other as reported by the Healthcare Cost and Utilization Project.

Discussion

This cross-sectional study revealed that during the winter of 2020-2021, for children aged 5 to 11 years, there was 1 MIS-C hospitalization for every COVID-19 hospitalization. This finding suggests that MIS-C may not be as rare of a COVID-19 sequela as previously thought. Other long-term COVID-19 complications may also be of concern for children aged 5 to 11 years. Although rarer than influenza infection, the extreme severity of MIS-C made the total economic and health burden of COVID-19 infection combined with MIS-C just as high as that of past influenza outbreaks. One study limitation was that the percentage of children aged 5 to 11 years who were Asian or Pacific Islander, Black, Hispanic, and other race and ethnicity for the studied 11 states was 39.4% compared with 50.2% for all US states. Thus, our data possibly underestimated the national rate and severity of MIS-C. It is our hope that our study results may provide important data points for public health planning efforts, including racial and ethnic minority group outreach, to help reduce the disease burden of both COVID-19/MIS-C and influenza.

Supplement.

eMethods. Diagnostic Codes

References

Associated Data

This section collects any data citations, data availability statements, or supplementary materials included in this article.

Supplementary Materials

Supplement.

eMethods. Diagnostic Codes


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