The Lancet Respiratory Medicine: Children with poorly controlled asthma at higher risk of COVID-19 hospitalisation and should be prioritised for vaccination
- Scottish study of over 750,000 school-aged children finds 5–17 year olds with poorly controlled asthma (who have been hospitalised with asthma or prescribed two or more courses of oral steroids for asthma within the past two years) are between three to six times more likely to be hospitalised with COVID-19 compared to those without asthma.
- Authors call for unvaccinated children with poorly controlled asthma to be prioritised for COVID-19 vaccination
Children with poorly controlled asthma infected with COVID-19 are more likely to require hospitalisation than children with well controlled asthma, or those without asthma. The national analysis is the first of its kind investigating COVID-19 hospitalisation among 5–17 year olds living in Scotland, UK, between March 2020 and July 2021.
The findings, published in The Lancet Respiratory Medicine journal, suggest that current UK recommendations to offer COVID-19 vaccination to all 12–17 year olds should now be expanded to include children with poorly controlled asthma aged 5 and older—including an estimated 109,488 in the UK.
The authors say that prioritising this group of children for COVID-19 vaccination has important implications for vaccine delivery worldwide by reducing the risk of COVID-19 infection, associated illness and consequently the need for children to have time off school. However, the overall risk of children with asthma becoming seriously ill with COVID-19 is low, with 1 in 380 children with poorly controlled asthma in the study hospitalised with COVID-19.
“Understanding which children with asthma are at increased risk of serious COVID-19 outcomes is critical to ongoing policy deliberations on vaccine prioritisation”, says lead author Professor Aziz Sheikh from the University of Edinburgh, Scotland. “Our analysis provides the first national evidence of the risk of COVID-19 hospitalisations among school-aged children with markers of poorly controlled asthma.”
He continues, “The key takeaway from this study is that keeping children’s asthma under control is critical as this greatly reduces the risk of COVID-19 hospitalisation. Vaccinating those with poorly controlled asthma offers an additional important layer of protection from serious COVID-19 outcomes.”
Asthma is one the most common long-term childhood conditions, affecting an estimated 78 million 5–19 year olds worldwide in 2019 , with over 1 million children being treated for asthma in the UK alone. Asthma has multiple triggers that can cause rapid worsening or chronic symptoms (eg, shortness of breath, coughing, and wheezing). Respiratory viruses are one of the most common asthma triggers, especially in children. Despite evidence that adults with poorly controlled asthma are at greater risk of being more severely affected by COVID-19, there is a lack of research in children, and until now, there have been no population-based analyses.
At the request of the UK’s Joint Committee on Vaccination and Immunisation (JCVI), researchers analysed data from the Scotland-wide Early Pandemic Evaluation and Enhanced Surveillance of COVID-19 (EAVE II) reporting platform between 1st March 2020 and 27th July 2021 to identify which children with asthma were at increased risk of severe COVID-19, leading to hospitalisation within 14 days of a positive real-time reverse transcription-polymerase chain reaction (PT-PCR) test, or death from any cause within 28 days after a positive test for SARS-CoV-2. EAVE II allows rapid analysis of data from routinely collected electronic health records and linked national databases for 5.4 million people (around 99% of the Scottish population).
In total, 752,867 children aged 5-17 years old were included in the analysis. Among 63,463 children (8.4%) with a diagnosis of asthma, 4,339 (6.8%) had a confirmed SARS-CoV-2 infection, and 67 (1.5%) of these were admitted to hospital with COVID-19. There were nine intensive care admissions or deaths in children with asthma, which prevented detailed evaluation of these most severe outcomes. Overall, 40,231 (5.8%) of children without asthma had a confirmed SARS-CoV-2 infection, of whom 382 (0.9%) were hospitalised with COVID-19.
The study found that 5-17 year olds with poorly controlled asthma (defined as being hospitalised with asthma within the past two years) were more likely to be admitted to hospital with COVID-19 (548 COVID-19 hospitalisations per 100,000 children), compared to children with well-controlled asthma (94 hospitalisations per 100,000 children), or without asthma (55 hospitalisations per 100,000 children).
Similar analyses were done using treatment with one or more courses of oral steroids (a medication commonly used to treat asthma attacks) over the past two years as the marker of uncontrolled asthma. 5–17 year-olds with uncontrolled asthma were more likely to be hospitalised due to COVID-19 (94 and 231 hospitalisations per 100,000 children for one and two courses respectively) compared to children without asthma (54 hospitalisations per 100,000 children).
After adjusting for factors that are known to be linked with increased risk of serious COVID-19 outcomes, including age, sex, socioeconomic status, other illnesses or conditions, and previous non-asthma related hospitalisations, researchers found that children who had recently been hospitalised with asthma were six times more likely to be admitted to hospital with COVID-19 than those without asthma, while children who had recently been prescribed oral steroids faced a three times higher risk of hospitalisation due to COVID-19.
Based on these data, the researchers estimate that there were 9,124 children aged 5–17 years old with poorly controlled asthma in Scotland during the study period who might have benefited from COVID-19 vaccination, and approximately 109,488 children in the whole UK (assuming the same prevalence of poorly controlled asthma in the other nations of the UK; table 1).
“Although COVID-19 tends to affect children less severely than adults, our findings underscore the importance of carefully monitoring these children if they become infected with COVID-19 and ensuring that children take their preventive inhalers regularly, go for asthma reviews, and have an up-to-date asthma treatment action plan”, says co-author Dr Ting Shi from the University of Edinburgh. “More research is needed to investigate the underlying mechanisms that predispose children to these increased risks of COVID-19 hospitalisation.” 
The authors note that there are some limitations to their study, including that they relied on surrogate markers of recent asthma hospitalisation or prescription of oral steroids that may not accurately identify all children with poorly controlled asthma. Moreover, it is possible that asthma control may have changed over the two-year study period, because of changes in behaviours or difficulties with access to care over the course of the pandemic. In addition, the authors note that they were unable to account for some potentially important confounders (such as tobacco exposure, unsuitable housing, and ethnicity) due to the lack of reliable recording of these social variables within electronic health records—which may have influenced the results.
Writing in a linked Comment, Rachel Harwood from Alder Hey in the Park, Liverpool, UK (who was not involved in the study) says, “Careful decision making around the delivery of the vaccine to children younger than 12 years is essential. Although children with asthma have been identified as having an increased risk of being admitted to hospital compared with peers without asthma, the overall risk remains very low. A balance between the risk of hospitalisation from SARS-CoV-2 and the low risk of vaccination side-effects needs to be carefully considered before vaccination is contemplated.”
She adds, “Over the coming winter, many well recognised respiratory viruses are anticipated in children, and in combination with seasonal changes, these are expected to increase the frequency and severity of asthma exacerbations. A focus on excellent asthma control, including the delivery of the influenza vaccine, and improving air quality and hygiene in schools is essential for all children with asthma to reduce their susceptibility to exacerbations over the coming winter.”
NOTES TO EDITORS
[The study was funded by UK Research and Innovation (Medical Research Council), Research and Innovation Industrial Strategy Challenge Fund, Health Data Research UK and the Scottish Government. It was conducted by researchers at the University of Edinburgh, Edinburgh, Scotland; University of Strathclyde, Glasgow, Scotland; University of Glasgow, Scotland; University of St Andrews, St Andrews, Scotland; Victoria University of Wellington, Wellington, New Zealand; University of Aberdeen, Aberdeen, Scotland; and Public Health Scotland, Glasgow, Scotland.