Epidemiological and clinical features of SARS‐CoV‐2 infection in children during the outbreak of Omicron variant in Shanghai, March 7–31, 2022

Abstract

Objectives: This study aimed to understand the epidemiological and clinical characteristics of pediatric SARS-CoV-2 infection during the early stage of Omicron variant outbreak in Shanghai. Methods: This study included local COVID-19 cases <18 years in Shanghai referred to the exclusively designated hospital from March 7 to March 31, 2022. Clinical data, epidemiological exposure, and COVID-19 vaccination status were collected. Relative risks (RRs) were calculated to assess the effect of vaccination on symptomatic infection and febrile disease. Results: A total of 376 pediatric cases of COVID-19 (median age: 6.0 AE 4.2 years) were referred to the designated hospital, including 257 (68.4%) symptomatic cases and 119 (31.6%) asymptomatic cases. Of the 307 (81.6%) children ≥3 years eligible for COVID-19 vaccination, 110 (35.8%) received two doses of vaccines. The median interval between the completion of two-dose vaccination and infection was 3.5 (interquartile range [IQR]: 3, 4.5) months. Compared with no vaccination, two-dose COVID-19 vaccination reduced the risks of symptomatic infection and febrile disease by 35% (RR 0.65, 95% confidence interval [CI]: 0.53-0.79) and 33% (RR 0.64, 95% CI: 0.51-0.81) among confirmed cases. Eighty-four percent of symptomatic cases had fever (mean duration: 1.7 AE 1.0.8 days), 40.5% had cough, and 16.4% had transient leukopenia. Three hundred and seven (81.6%) had an epidemiological exposure in household (69.1%), school (21.8%), and residential area (8.8%). Conclusion: The surge of pediatric COVID-19 cases and multiple transmission model reflect wide dissemination of Omicron variant in the community. Asymptomatic infection is common among Omicron-infected children. COVID-19 vaccination can offer some protection against symptomatic infection and febrile disease. Xiangshi Wang and Hailing Chang contributed equally to this article.

Clinical characteristics of children with omicron SARS-CoV-2 infection in Changchun, China from march to april 2022: A retrospective study

“…For example, in the Qatar cohort, 54.6% of children were female ( 16 ). Other female proportion, such as 55.0% in Spain ( 12 ), 45.2% in Shanghai ( 13 ), and 47.3% in the USA ( 14 ) were also reported, displaying an equal distribution. However, this finding is not consistent with the COVID-19 in the adult.…”

“…Moreover, during that year, a small cohort of children infected with Omicron was reported in the UK ( n = 55) ( 11 ) and Spain ( n = 15) ( 12 ). During an outbreak of Omicron variant in Shanghai, beginning March 7, 2022, a total of 376 children with Omicron was reviewed and reported in preprint without complete peer review ( 13 ). However, in 2021, large cohorts of childhood COVID-19 were reported.…”

“…Similar findings were observed in adulthood COVID-19 caused by the Omicron variant, which is that most patients have mild presentation ( 21 , 22 ). In Shanghai, approximately one-third of Omicron-infected children were asymptomatic, and no severe disease was diagnosed ( 13 ). Wang et al found that most children (82.9%) infected with Omicron variant had mild symptoms, mainly respiratory infection ( 23 ), which is consistent with the study by Ma et al ( 24 ).…”

“…Jeane et al (8) reported that children infected with the Omicron variant have a mean age of 4.2 years (SD 4.1) (8). In the USA COVID-19 cohort, the Omicron cohort was younger than the Delta cohort (14), and in most studies (12,13,16), the median age of Omicron children is reportedly between 6 and 7 years. In addition, our data also demonstrated that there was no significant difference in clinical types among age groups.…”

Clinical features of infants with SARS-CoV-2 infection: a systematic review and meta-analysis

“…The variant led to a higher rate of pediatric hospitalizations in children younger than 17 years (70). A recent study reported that 13.5% (14/104) of children (age <3 years) with SARS-CoV-2 infection were asymptomatic cases during the outbreak of Omicron (71). However, the number of published studies of infants infected with the Omicron variant is limited in issued studies.…”