Hong Kong Med J 2021 Dec;27(6):461–3  |  Epub 17 Dec 2021
© Hong Kong Academy of Medicine. CC BY-NC-ND 4.0
Critically ill children in paediatric intensive care unit are no less susceptible to infectious diseases amid the COVID-19 pandemic
Karen KY Leung, MB, BS, MRCPCH1; KL Hon, MB, BS, MD1; Patrick Ip, MB, BS, MD2; Renee WY Chan, PhD3,4,5,6
1 Paediatric Intensive Care Unit, Department of Paediatrics and Adolescent Medicine, The Hong Kong Children’s Hospital, Hong Kong
2 Department of Paediatrics and Adolescent Medicine, The University of Hong Kong, Hong Kong
3 Department of Paediatrics, The Chinese University of Hong Kong, Hong Kong
4 Hong Kong Hub of Paediatric Excellence, The Chinese University of Hong Kong, Hong Kong
5 Laboratory for Paediatric Respiratory Research, Li Ka Shing Institute of Health Sciences, The Chinese University of Hong Kong, Hong Kong
6 CUHK-UMCU Joint Research Laboratory of Respiratory Virus & Immunobiology, Department of Paediatrics, The Chinese University of Hong Kong, Hong Kong
Corresponding author: Dr KL Hon (ehon@hotmail.com)
 Full paper in PDF
With the lifting of various measures intended to limit the spread of coronavirus disease 2019 (COVID-19), paediatric cases have been on the rise, with approximately 2% to 6% of those infected becoming critically ill.1 2 3 4 5 6 During the early phase of the pandemic, a review of 2135 paediatric cases in China revealed the proportion of severe and critical illness to be higher in the younger age-group, in particular infants.5 In a separate report by the United States Centers for Disease Control and Prevention, 62% of those aged <1 year were hospitalised compared with 4.1% to 14% among those aged 1 to 17 years.6 However as the pandemic evolves, the epidemiology seems to have changed and COVID-19 is now affecting older children more severely. In the latest report from the United States, critically ill children with COVID-19 were predominantly adolescents, had co-morbidities, and required some form of respiratory support.7 In many cases, the presence of acute respiratory distress syndrome was associated with prolonged paediatric intensive care (PICU) and hospital stay.8
Recently there has been an emergence of paediatric hyperinflammatory and shock syndromes including paediatric inflammatory multisystem syndrome (PIMS), MIS-C (multisystem inflammatory syndrome in children), and PIMS-TS (paediatric inflammatory multisystem syndrome temporally associated with severe acute respiratory syndrome coronavirus 2 [SARS-CoV-2]).9 10 These are systemic diseases involving persistent fever, inflammation and organ dysfunction associated with SARS-CoV-2; 80% of the patients with this new disease entity require intensive care support with a 2% fatality rate.3 11 12 13 Furthermore, COVID-19 is associated with dysfunction across many organ systems as in PIMS as well as syndromes such as COVID stress syndrome and COVID toe syndrome.14
Unlike other respiratory viruses such as influenza and respiratory syncytial virus, there has fortunately been no paediatric mortality due to COVID-19 in Hong Kong. We reviewed all admissions to the Hong Kong Children’s Hospital PICU with nasal pharyngeal swab/aspiration for SARS-CoV-2 between 1 February and 6 September 2020, and found that 22 (16.3%) of our admitted patients were tested and they were all negative for COVID-19 (Table 1). During the early stages of the COVID-19 epidemic in Hong Kong, screening for COVID-19 was not universal for all PICU admissions; only patients meeting set criteria were screened, primarily in-patients, patients acutely admitted, or patients transferred in who had not already been tested. Patients who had been tested negative elsewhere or in-patients with no exposure were not tested in the initial phase of the pandemic. During the same period, there were 441 (9%) of COVID-19 cases in Hong Kong were aged ≤18 years (Table 2 15). In addition to SARS-CoV-2, various viral and bacterial pathogens were isolated in these paediatric patients with COVID-19. Viruses isolated include adenovirus, Epstein-Barr virus, and BK virus in blood samples; rhinovirus, enterovirus, and cytomegalovirus in respiratory specimens; and BK virus in urine samples. A wide variety of bacteria were also isolated, including a case of hyperinflammatory hemophagocytic lymphohistiocytosis syndrome due to Orientia tsutsugamushi instead of SARS-CoV-2. Compared with paediatric patients with SARS-CoV-2 in the community, viral and bacterial infections were present in 22.7% and 50% of SARS-CoV-2 negative patients in our PICU cohort, respectively (P<0.001). The COVID-19 screening criteria changed as the pandemic evolved and it is now mandatory to screen every patient admitted to the PICU for COVID-19.

Table 1. Patients admitted to Hong Kong Children’s Hospital PICU, 1 February to 6 September 2020

Table 2. Cases of coronavirus disease 2019 in Hong Kong (n=4879), 1 February to 6 September 2020 16
In our opinion, it is unlikely that PICUs in Hong Kong have missed any cases of COVID-19. During the pandemic, it is easy to overestimate the prevalence of COVID-19 due to cognitive bias, and assume all patients with fever are infected with COVID-19 until proven otherwise, leading to potential therapeutic errors.16 However, our observations have concluded that critically ill children are susceptible to contracting a whole host of infectious diseases. Therefore, in addition to screening for COVID-19, physicians must also be vigilant of other pathogens that could affect critically ill children, and duly take antimicrobial and isolation precautions within healthcare environments. It appears that SARS-CoV-2 infection is generally an asymptomatic or very mild disease in children. In contrast, serious viral and bacterial infections are associated with critically ill children tested negative for SARS-CoV-2.
Author contributions
All authors contributed to the concept or design, acquisition of data, analysis or interpretation of data, drafting of the manuscript, and critical revision of the manuscript for important intellectual content. All authors had full access to the data, contributed to the study, approved the final version for publication, and take responsibility for its accuracy and integrity.
Conflicts of interest
As the editor of the journal, KL Hon was not involved in the peer review process for the article. Other authors have no conflicts of interest to disclose.
This study received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.
1. Hon KL, Leung KK. Paediatrics is a big player of COVID-19 in Hong Kong [Letter]. Hong Kong Med J 2020;26:265-6. Crossref
2. Hon KL, Leung KK. Pediatric COVID-19: what disease is this? World J Pediatr 2020;16:323-5. Crossref
3. Hon KL, Leung KK, Leung AK, et al. Overview: the history and pediatric perspectives of severe acute respiratory syndromes: novel or just like SARS. Pediatr Pulmonol 2000;55:1584-91. Crossref
4. Wu Z, McGoogan JM. Characteristics of and important lessons from the coronavirus disease 2019 (COVID-19) outbreak in China: summary of a report of 72314 cases from the Chinese Center for Disease Control and Prevention. JAMA 2020;323:1239-42. Crossref
5. Dong Y, Mo X, Hu Y, et al. Epidemiology of COVID-19 among children in China. Pediatrics 2020;145:e20200702. Crossref
6. CDC COVID-19 Response Team. Coronavirus Disease 2019 in children—United States, February 12-April 2, 2020. MMWR Morb Mortal Wkly Rep 2020;69:422-6. Crossref
7. Derespina KR, Kaushik S, Plichta A, et al. Clinical manifestations and outcomes of critically ill children and adolescents with Coronavirus Disease 2019 in New York City. J Pediatr 2020;226:55-63.e2. Crossref
8. Pathak EB, Salemi JL, Sobers N, Menard J, Hambleton IR. COVID-19 in children in the United States: intensive care admissions, estimated total infected, and projected numbers of severe pediatric cases in 2020. J Public Health Manag Pract 2020;26:325-33. Crossref
9. Joshi K, Kaplan D, Bakar A, et al. Cardiac dysfunction and shock in pediatric patients with COVID-19. JACC Case Rep 2020;2:1267-70. Crossref
10. Riphagen S, Gomez X, Gonzalez-Martinez C, Wilkinson N, Theocharis P. Hyperinflammatory shock in children during COVID-19 pandemic. Lancet 2020;395:1607-8. Crossref
11. Feldstein LR, Rose EB, Horwitz SM, et al. Multisystem inflammatory syndrome in U.S. Children and Adolescents. N Engl J Med 2020;383:334-6. Crossref
12. Paediatric Intensive Care Society. PICS Statement: increased number of reported cases of novel presentation of multi system inflammatory disease. 2020. Available from: https://pccsociety.uk/wp-content/uploads/2020/04/PICS-statement-re-novel-KD-C19-presentation-v2-27042020.pdf. Accessed 25 Sep 2020.
13. The Royal College of Paediatrics and Child Health. Paediatric multisystem inflammatory syndrome temporally associated with COVID-19 (PIMS)—guidance for clinicians. 2020. Available from: https://www.rcpch.ac.uk/resources/paediatric-multisystem-inflammatory-syndrome-temporally-associated-covid-19-pims-guidance. Accessed 25 Sep 2020.
14. Rose-Sauld S, Dua A. COVID toes and other cutaneous manifestations of COVID-19. J Wound Care 2020;29:486-7. Crossref
15. Centre for Health Protection, Hong Kong SAR Government. Latest situation of cases of COVID-19 (as of 24 September 2020). 2020. Available from: https://www.chp.gov.hk/files/pdf/local_situation_covid19_en.pdf. Accessed 24 Sep 2020.
16. Zagury-Orly I, Schwartzstein RM. Covid-19—A reminder to reason. N Engl J Med 2020;383:e12. Crossref