TABLE 2. Clinical characteristics and outcomes among infants and children aged 0–4 years hospitalized with laboratory-confirmed COVID-19 (N = 572),* by age group, during Omicron predominance — COVID-NET, 14 states,^† December 19, 2021–January 31, 2022.

Characteristic	No. (%) of hospitalizations, by age group				P-value§
	Total	<6 mos	6–23 mos	2–4 yrs
Total no. of hospitalized infants and children	572 (100)¶	252 (44)¶	180 (32)¶	140 (24)¶	NA
Primary reason for admission**
Likely COVID-19–related	485 (84.8)	210 (83.3)	159 (89.2)	116 (81.8)	0.23
COVID-19–related symptoms at admission††
Yes	502 (86.9)	211 (82.0)§§	163 (91.9)	128 (89.2)	0.04
Symptoms at admission
Fever/chills	340 (60.3)	128 (51.0)	123 (70.8)	89 (63.2)	0.001
Cough	317 (55.6)	119 (45.6)	120 (70.8)	78 (53.7)	<0.001
Congested/Runny nose	290 (52.1)	135 (51.3)	98 (61.1)	57 (41.6)	0.01
Shortness of breath/Respiratory distress	201 (34.7)	85 (31.0)	74 (43.8)	42 (29.3)	0.02
Inability to eat/Poor feeding	139 (29.2)	75 (26.6)	64 (32.6)	—¶¶	0.21
Nausea/Vomiting	148 (26.6)	40 (18.1)	59 (31.8)	49 (35.4)	0.003
Fatigue	83 (13.4)	21 (6.6)	25 (13.7)	37 (25.2)	<0.001
Decreased vocalization/Stridor	49 (11.6)	15 (5.8)	34 (19.7)	—¶¶	<0.001
Seizures	27 (3.9)	4 (1.5)	9 (5.0)	14 (6.9)	0.02
Underlying medical condition
One or more underlying medical condition***	220 (36.6)	66 (26.3)	80 (40.3)	74 (50.4)	<0.001
Prematurity	74 (17.1)	39 (16.7)	35 (17.7)	—¶¶	0.83
Neurologic disorders	60 (10.0)	10 (3.6)	17 (8.9)	33 (23.0)	<0.001
Congenital heart disease	49 (8.6)	18 (7.1)	19 (9.2)	12 (10.5)	0.62
Chronic lung disease, including asthma	35 (5.8)	5 (2.5)	12 (5.3)	18 (12.6)	<0.001
Immunocompromised condition	18 (3.2)	1 (0.5)	5 (1.9)	12 (9.7)	<0.001
Chronic lung disease of prematurity/BPD	18 (2.6)	4 (1.8)	7 (2.6)	7 (4.3)	0.32
Chronic metabolic disease	15 (2.5)	2 (0.7)	5 (2.8)	8 (5.3)	0.02
Abnormality of airway	11 (1.4)	4 (1.2)	5 (1.8)	2 (1.3)	0.85
Viral codetection†††
RSV	30 (7.3)	22 (12.7)	6 (4.3)	2 (2.0)	0.003
Influenza	7 (1.3)	4 (1.3)	1 (0.8)	2 (2.1)	0.62
Rhinovirus/Enterovirus	34 (10.7)	13 (10.6)	10 (8.4)	11 (13.5)	0.59
Other viral infections	28 (9.0)	4 (3.2)	14 (13.4)	10 (12.2)	0.03
Hospitalization outcome§§§
Length of hospital stay, days, median (IQR)	1.5 (0.5–2.5)	1.5 (1–2.5)	1.5 (0.5–3)	1.5 (0.5–3)	0.70
ICU admission	124 (21.0)	57 (21.6)	39 (21.9)	28 (18.9)	0.81
BiPAP/CPAP	31 (5.1)	12 (4.5)	12 (6.1)	7 (4.8)	0.76
High flow nasal cannula	84 (13.4)	43 (14.1)	28 (16.1)	13 (8.7)	0.20
Invasive mechanical ventilation	29 (5.2)	10 (4.6)	11 (5.9)	8 (5.6)	0.84
In-hospital death	2 (0.5)	2 (1.1)	0 (—)	0 (—)	0.70

Abbreviations: BiPAP/CPAP = bilevel positive airway pressure/continuous positive airway pressure; BPD = bronchopulmonary dysplasia; COVID-NET = Coronavirus Disease 2019–Associated Hospitalization Surveillance Network; ICU = intensive care unit; NA = not applicable; RSV = Respiratory syncytial virus.

* Data are from a weighted sample of hospitalized infants and children with completed medical record abstractions. Sample sizes presented are unweighted with weighted percentages.

^† Includes persons admitted to a hospital with an admission date during December 19, 2021–January 31, 2022. Counties included in COVID-NET surveillance during this period: California (Alameda, Contra Costa, and San Francisco counties); Colorado (Adams, Arapahoe, Denver, Douglas, and Jefferson counties); Connecticut (Middlesex and New Haven counties); Georgia (Clayton, Cobb, DeKalb, Douglas, Fulton, Gwinnett, Newton, and Rockdale counties); Iowa (one county represented); Michigan (Clinton, Eaton, Genesee, Ingham, and Washtenaw counties); Minnesota (Anoka, Carver, Dakota, Hennepin, Ramsey, Scott, and Washington counties); New Mexico (Bernalillo, Chaves, Doña Ana, Grant, Luna, San Juan, and Santa Fe counties); New York (Albany, Columbia, Genesee, Greene, Livingston, Monroe, Montgomery, Ontario, Orleans, Rensselaer, Saratoga, Schenectady, Schoharie, Wayne, and Yates counties); Ohio (Delaware, Fairfield, Franklin, Hocking, Licking, Madison, Morrow, Perry, Pickaway and Union counties); Oregon (Clackamas, Multnomah, and Washington counties); Tennessee (Cheatham, Davidson, Dickson, Robertson, Rutherford, Sumner, Williamson, and Wilson counties); and Utah (Salt Lake county).

^§ Proportions of infants and children aged <6 months, 6–23 months, and 2–4 years were compared using chi-square tests, and medians were compared using the Wilcoxon rank-sum test; p-values <0.05 were considered statistically significant.

^¶ Data are missing for <6% of observations for all variables, except for viral codetections.

** Among sampled patients, COVID-NET collects data on the primary reason for admission to differentiate hospitalizations of patients with laboratory-confirmed SARS-CoV-2 infection who are likely admitted primarily for COVID-19 illness versus other reasons. During chart review, if the surveillance officer found that the chief complaint or history of present illness mentions fever/respiratory illness, COVID-19–like illness, or a suspicion for COVID-19, then the case was categorized as COVID-19–related illness as the primary reason for admission. Reasons for admission that are likely primarily not COVID-19–related include categories such as inpatient surgery or trauma. Infants with COVID-19 diagnosed during their birth hospitalization were not categorized as likely COVID-19–related unless they exhibited COVID-19–related symptoms.

^†† COVID-19–related symptoms included respiratory symptoms (congested/runny nose, cough, hemoptysis/bloody sputum, shortness of breath/respiratory distress, sore throat, upper respiratory infection, influenza-like illness, and wheezing) and non-respiratory symptoms (abdominal pain, altered mental status/confusion, anosmia/decreased smell, chest pain, conjunctivitis, diarrhea, dysgeusia/decreased taste, fatigue, fever/chills, headache, muscle aches/myalgias, nausea/vomiting, rash, and seizures, and among those aged <2 years: apnea, cyanosis, decreased vocalization/stridor, dehydration, hypothermia, inability to eat/poor feeding, and lethargy). Symptoms are abstracted from the medical chart and might be incomplete.

^§§ Among the 250 hospitalizations among infants aged <6 months with complete data on birth hospitalization, 14% (31 of 250) were birth hospitalizations. Of these birth hospitalizations, 91% (28 of 31) had no symptoms recorded. If birth hospitalizations are excluded, 94% (208 of 219) infants aged <6 months had symptoms recorded.

^¶¶ Cyanosis, decreased vocalization/stridor, inability to eat/poor feeding, and lethargy are symptoms that are only recorded for infants and children aged <2 years. Prematurity is an underlying medical condition only reported for infants and children aged <2 years.

*** Defined as one or more of the following: chronic lung disease, chronic metabolic disease, blood disorder/hemoglobinopathy, cardiovascular disease, neurologic disorder, immunocompromised condition, renal disease, gastrointestinal/liver disease, rheumatologic/autoimmune/inflammatory condition, obesity, feeding tube dependency, or wheelchair dependency.

^††† Results reported among infants and children who had testing performed (as opposed to all hospitalized infants and children). Because of differing testing practices, denominators differed among the viral respiratory pathogens: 424 infants and children were tested for RSV, 440 for influenza (influenza A, influenza B, flu [not subtyped]), 260 for rhino/enterovirus, and 261 for other viruses (adenovirus, parainfluenza 1, parainfluenza 2, parainfluenza 3, parainfluenza 4, and human metapneumovirus).

^§§§ Hospitalization outcomes are not mutually exclusive; patients could be included in more than one category.