Severe COVID-19, Prolonged Viral Shedding More Likely in Younger Children

Among children infected with the SARS-CoV-2 Omicron variant, those younger than 3 years were more likely to develop severe infection and experience prolonged viral shedding.

Younger children who are ineligible for COVID-19 vaccination may be at increased risk for moderate to severe infection with the SARS-CoV-2 Omicron variant with prolonged viral shedding, according to study results published in International Journal of Infectious Diseases.

Researchers evaluated the epidemiologic, clinical, and household transmission characteristics of the Omicron variant of SARS-CoV-2 among hospitalized pediatric patients in Shanghai, China.

The retrospective multicenter study was conducted between March and May 2022. Patient data were captured from electronic health records and via telephone interviews. The primary outcome was the clinical severity of COVID-19 infection among patients in 4 age groups (<3, 3-5, 6-11, and 12-17 years). Risk factors associated with the occurrence of moderate to severe infection were assessed via multivariate logistic regression, with adjustments for age, sex, BMI, vaccination status, underlying conditions, and allergy history.

Among 2620 patients included in the analysis, the mean age was 6.7 years (range, 24 days to 17 years); 45% were girls; and 23% were admitted to makeshift hospitals. Of the total cohort, 38.6% were asymptomatic, 54.0% had mild infection, 7.3% had moderate infection, and 0.2% had severe infection.

The most common symptoms among symptomatic patients (n=1609) included fever, cough, rhinorrhea, expectoration, and abnormal bowel movement. Further analysis showed that 64.2% of patients reported household exposure to at least 1 adult with confirmed COVID-19 infection, and 28.7% were the first within their household to develop the infection.

Analysis of 1002 symptomatic patients with data on household transmission and vaccination status indicated a mean household infection rate of 85.1%.

These findings may facilitate the development of future COVID-19 prevention and control strategies in China.

Risk for moderate to severe infection was significantly higher among patients younger than 3 years compared with those aged between 12 and 17 years (adjusted odds ratio [aOR], 11.07; 95% CI, 3.68-33.25). Other risk factors for moderate to severe infection in children included obesity (aOR, 2.32; 95% CI, 1.24-4.33) and comorbid conditions (aOR, 3.51; 95% CI, 2.11-5.85). The risk also was significantly increased among unvaccinated patients compared with those who received at least 1 vaccine dose (aOR, 3.58; 95% CI, 1.50-8.54).

The longest duration of viral shedding was observed in patients younger than 3 years, and the mean duration was 1.42 days longer among unvaccinated vs vaccinated patients (P <.001).

Study limitations include the use of self-reported data, potential overestimation of the household infection rate, and limited generalizability to other pediatric populations.

According to the researchers, “These findings may facilitate the development of future COVID-19 prevention and control strategies in China.


Liu Y, Xu L, Piao X, et al. Epidemiological, clinical and household transmission characteristics of children and adolescents infected with SARS-CoV-2 Omicron variant in Shanghai, China: a retrospective multicenter observational study. Int J Infect Dis. Published online January 29, 2023. doi:10.1016/J.ijid.2023.01.030