Risk factors for intensive care admission and death amongst children and young people admitted to hospital with COVID-19 and PIMS-TS in England during the first pandemic year
Authors: Ward J L , Harwood R , Smith C , Kenny S , Clark M , Davis PJ , Draper ES , Hargreaves D , Ladhani S , Linney M , Luyt K , Turner S , Whittaker E , Fraser L K , Viner R.M 
Published: July 2021

Identifying which children and young people (CYP) are vulnerable to severe disease following SARS-CoV-2 is important to guide shielding and vaccination policy.

Methods

We used data for all inpatient hospital admissions in England in CYP aged 0-17 between March 1st2015 to Feb 28th2021, linked to paediatric intensive care unit (PICU), SARS-CoV-2 PCR testing, and mortality data. We examined associations between PICU admission and death by sociodemographic factors and comorbidities within COVID-19 and PIMS-TS admissions. We calculated odds ratios and predicted probability of PICU admission using generalized estimation equations, and compared these between COVID-19, PIMS-TS, other admissions in 2020/21, all admissions in 2019/20, and admissions due to influenza in 20219/20. Analyses of deaths were descriptive due to low numbers.

Findings

Within COVID-19, there were 6,338 hospital admissions, 259 PICU admissions and 8 deaths. Within PIMS-TS there were 712 hospital admissions 312 PICU admissions and <5 deaths. Males were 52.8% of COVID-19 admissions (similar to other causes of admission), but were 63.5% of PIMS-TS admissions. CYP aged 10-17 were 35.6 and 29% of COVID-19 and PIMS-TS admissions respectively, higher than in all admission and influenza admissions in 2019/20. In multivariable models, odds of PICU admission were: increased amongst neonates and decreased amongst 15-17 compared with 1-4 year olds with COVID-19, increased in older CYP and females with PIMS-TS, and increased for Black compared with White ethnicity in COVID-19 and PIMS-TS. Odds of PICU admission with COVID-19 were increased for CYP with any comorbidity and were highest for CYP with multiple medical problems. Increases in risk of PICU admission associated with comorbidities showed similar patterns for COVID-19 and all admissions in 2019/20 and influenza admissions in 2019/20, but were greater for COVID-19. Interpreting associations with comorbidities within PIMS-TS was complex due to the multisystem nature of the disease.

Interpretation

CYP were at very low risk of severe disease and death from COVID-19 or PIMS-TS. PICU admission due to PIMS-TS was associated with older non-white CYP. Patterns of vulnerability for severe COVID-19 appear to magnify background risk factors for serious illness in CYP.

Evidence before this study

We conducted a systematic review and meta-analysis of studies investigating risk factors associated with severe disease among children and young people admitted with COVID-19 and PIMS-TS, [Harwood, R et al. 2021 (submission to the Lancet linked with this paper)]. We identified 81 studies. Infants were found to have increased odds of PICU admission compared with 1-4, but there were no associations by sex. Other factors associated with PICU admission included number of co-morbid conditions, with neurological, cardiac and gastrointestinal associated with the greatest risk. Low numbers of serious SARS-CoV-2 infections or deaths amongst CYP limit these analyses, yet national studies of CYP have not yet been published. Importantly, we found these studies did not take into account background risks for severe illness in CYP who are known to be vulnerable before the pandemic.

What this study adds

This is the first population base study of risk factors for severe disease following SARS-CoV-2 infection in CYP in England. We analyse all admissions to hospital amongst 0-17 year olds nationally between 2015-2021 linked to multiple other health datasets. We explore how socioeconomic factors and co-morbidities are associated with Paediatric Intensive Care Unit (PICU) admission and death amongst CYP admitted with COVID-19 and PIMS-TS, and compare this with other causes for admission during the pandemic and in the year prior. As CYP with PIMS-TS are highly likely to require hospitalization, we were able to analyse total national cases of the condition during 2020/21.

We found extremely low numbers of CYP required PICU or died as a result of SARS-CoV-2 in the first pandemic year. CYP admitted due to COVID-19 disease were older and more likely to be non-white with pre-existing conditions, similar to patterns seen in adults. Patterns of associations between comorbidities and risk of PICU admission amongst COVID-19 were similar to those seen for all admissions and influenza admissions in the year prior to the pandemic. However, the increase in risk associated with comorbidities for COVID-19 admissions were greater than in these cohorts.

We found most cases of PIMS-TS were amongst non-white male adolescents without previous hospital admissions. Interpreting associations between comorbidities and PICU admission for PIMS-TS was complicated by the multi-system nature of the disease.

Implications of all the available evidence

CYP with most vulnerable to COVID-19 were also those most at risk of prior to the pandemic due to other illnesses such as influenza, although COVID-19 appears to amplify this risk profile. It is important to consider this context when advising parents and carers regarding the risk posed by COVID-19, considering potential harms to CYP as a result of shielding precautions.