Discussion
In this single centre prospective study, similar rates of cardiac and respiratory disease were observed in children infected with SARS-CoV-2 compared to uninfected.
In addition, those with a history of cardiac or respiratory disease were no more likely, than those without, to present with symptomatic infection. Our findings support those of other studies indicating that children with SARS-CoV-2 infection generally experience mild symptoms and that many have asymptomatic infection [5-8]. We have also shown that rates of asymptomatic infection are similar in children with and without cardiorespiratory comorbidities.
Interestingly, we also observed a high proportion of hospitalised children with SARS-CoV-2[+] infection had a history of cardiac disease (23.8%). This raises the question of whether the primary reason for increased rate of hospitalisation for these children is the result of their pre-existing cardiac disease, increasing susceptibility to more severe forms of infection, or if admission was for precautionary reasons. Recent data suggests that pre-existing cardiac disease in children is associated with hospitalisation, ICU admission and mechanical ventilation [9-11]. A systematic review by Williamset al showed high rates of cardiac disease (n=11/48; 23%) in children and adolescents with COVID-19 requiring hospitalisation and mechanical ventilation [10]. Furthermore the authors also reported that cardiac disease requiring prior surgical intervention was associated with more severe forms of SARS-CoV-2 infection and higher rates of hospitalisation [10]. Cardiac disease was also shown to be associated with ICU admission in a recent European multicentre study [11]. In contrast, whilst asthma was also common in the SARS-CoV-2[+] cohort, only two (9.5%) children who were hospitalised with COVID-19 reported a history of asthma. Similar findings have been reported in another observational study. [12]
While symptom profiles of SARS-CoV-2[+] and SARS-CoV-2[-] groups were similar (table 1) SARS-CoV-2[-] children were more likely, than SARS-CoV-2[+] children, to report a “runny nose”, shortness of breath and/or reduced appetite. In contrast, SARS-CoV-2[+] children more commonly reported diarrhoea than the SARS-CoV-2[-] group (6.2% vs 2%; p = 0.011). Rates of cough were similar between groups and in those with and without cardiorespiratory disease (data not shown).
There are several strengths to this study. First, testing was performed in a single paediatric hospital where healthcare workers and laboratory staff adhere to strict guidelines of sample collection and processing. Second, compared to community-based settings, there was likely to be a higher proportion of children with pre-existing comorbidities, as hospital-based testing clinics generally attract patients of the hospital, we acknowledge however that this strength is simultaneously a limitation of our study as parents of children with pre-existing comorbidities may have preferentially presented to the RCH over their local testing centre, potentially introducing selection bias. Third, due to the low prevalence of COVID-19 in Australia, our sample size is small, however this is balanced by the high level of case ascertainment in Australia which increases the generalisability of our findings.
In conclusion, pre-existing cardiac or respiratory disease did not appear to increase susceptibility to SARS-CoV-2 infection. Furthermore, children with, compared to those without, respiratory diseases had similar rates of symptomatic COVID-19. The high rates of pre-existing cardiac disease observed in hospitalised children with SARS-CoV-2 infection warrants further study.
Funding/Support: This study was supported by Murdoch Children’s Research Institute, Centers of Excellence in Influenza Research and Surveillance - Cross-Center Southern Hemisphere Project, The Influenza Complications Alert Network Surveillance System, Paediatric Active Enhanced Disease Surveillance and Sentinel Travelers and Research Preparedness Platform for Emerging Infectious Disease.