COVID-19 hospitalizations among children likely overcounted, researchers find

Children being treated in hospitals are tested for SARS-CoV-2, but many who test positive never develop COVID-19 symptoms, leading to overestimates of disease severity, a study found.

- By Erin Digitale

Children being treated in hospitals are tested for SARS-CoV-2, but many who test positive never develop COVID-19 symptoms.
Komsan Loonprom/

Counting SARS-CoV-2 infections in hospitalized children overestimates the impact of COVID-19 in pediatric populations because such counts include many asymptomatic patients, according to a new study by researchers at the Stanford University School of Medicine

The findings were published online May 19 in Hospital Pediatrics. While all hospitalized children are now being tested for SARS-CoV-2, nearly half of those who test positive for the virus never develop symptoms of COVID-19, according to the study.

“It’s really important that we distinguish between children who are hospitalized with asymptomatic SARS-CoV-2 infections and those hospitalized for COVID-19 disease,” said Alan Schroeder, MD, a co-author of the paper and clinical professor of pediatric critical care and of pediatric hospital medicine. “Our goal is to make sure we have accurate data on how sick children are getting. If we rely on hospitals’ positive SARS-CoV-2 test results, we are inflating by about two-fold the actual risk of hospitalization from the disease in kids.”

Lauren Kushner, MD, medical fellow in pediatric infectious diseases, is lead author of the study. The senior author is Roshni Mathew, MD, clinical associate professor of pediatric infectious diseases.

Since the COVID-19 pandemic began, children have been less likely than adults to catch the virus or to develop symptoms when infected. They are also much less likely to become sick enough with COVID-19 to require hospitalization. 

Throughout the pandemic, however, many have developed other conditions that require hospital care, from common childhood complaints, such as broken bones and appendicitis, to rarer illnesses, such as pediatric cancers. And when they come to the hospital and are tested for SARS-CoV-2, some turn out to be infected. 

Nine months of hospital data

The researchers analyzed COVID-19 data from Lucile Packard Children’s Hospital Stanford between May 10, 2020, when the hospital implemented universal COVID-19 testing for all inpatients, and Feb. 10, 2021.

During the nine-month period, 117 children either had a positive test for the SARS-CoV-2 virus or were hospitalized for MIS-C, the multi-system inflammatory syndrome in children that can follow viral infection by weeks. 

Of the 117 patients, 46 (39.3%) had asymptomatic COVID-19, 33 (28.2%) had mild to moderate disease, 9 (7.7%) had severe illness, 15 (12.8%) had critical illness and 14 (12%) had MIS-C. Patients with mild to moderate disease had COVID symptoms but did not need supplemental oxygen, those with severe disease needed oxygen but not ventilation, and those with critical illness needed ventilation and may have had sepsis or multi-organ failure. 

The researchers reviewed the medical charts of each child in detail, doing their best to determine which of the 117 hospital admissions were unlikely to have been caused by SARS-CoV-2. They concluded that 53 of the patients (45%) were admitted for reasons unrelated to the virus.

Mathew noted that the percentage of positive tests in a children’s hospital is a better measure of SARS-CoV-2’s prevalence in the community than the rate at which kids fall ill with COVID-19. “The higher the prevalence, the higher the likelihood that anyone who has to come to the hospital is going to test positive,” she said. “Just knowing that a child is hospitalized and has the virus is not enough information to determine if they are actually sick with COVID-19.”

The researchers hope their findings will be used to improve the accuracy of public health records for COVID-19. Vaccinations, which are now available for children as young as 12 and are being tested in children 6 months through 11 years of age, are an effective means of combatting the pandemic, they added. 

Joseph Kim, MD, clinical associate professor of pediatrics and chief of pediatric hospital medicine, was also a co-author of the study. 

About Stanford Medicine

Stanford Medicine is an integrated academic health system comprising the Stanford School of Medicine and adult and pediatric health care delivery systems. Together, they harness the full potential of biomedicine through collaborative research, education and clinical care for patients. For more information, please visit

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