Childhood asthma is not a risk factor for COVID-19

The coronavirus disease 2019 (COVID-19) is caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which typically results in mild or asymptomatic infection. In a sizable minority of cases, however, SARS-CoV-2 infection can lead to severe or critical disease, with a fatal outcome in some.

Risk factors suggested or known to be associated with severe COVID-19 include asthma, diabetes, and hypertension, among others. A new study published on the preprint server medRxiv* provides new insights on the association of asthma and COVID-19, with the reassuring conclusion that this condition is not linked to a higher risk of adverse outcomes following COVID-19.

Study: Childhood Asthma and COVID-19: A Nested Case-Control Study. Image Credit: Ann in the uk / Shutterstock.com

Background

Asthma is a chronic inflammatory condition characterized by episodic reversible obstruction of the airways due to bronchospasm. In many cases, asthma first occurs in childhood, with a waxing and waning course.

There has been much discussion on whether asthma increases the risk of COVID-19, or predisposes the affected individual to severe disease. The fact that the majority of documented COVID-19 cases have occurred in adults does not help to arrive at a conclusion in this matter.

Since July 2021, pediatric COVID-19 has been on the rise, largely as a result of the dominance of the SARS-CoV-2 Delta variant that is more transmissible, along with the re-opening of schools. The latter has led to the mixing of millions of non-vaccinated children in-person, with or without masks, and without any uniformity in the nature and rigor of containment measures.

This makes it important to understand how COVID-19 affects children, especially those with asthma. The current study goes beyond the effects of masks, air pollution, social distancing, to focus on childhood asthma and COVID-19 incidence.

The study drew data from the Western Pennsylvania COVID-19 Registry (WPACR) database that began in March 2020, on children aged up to 21 years who had a SARS-CoV-2 diagnosis or features of the multisystem inflammatory syndrome in children (MIS-C), and presented to the primary or referral care facility under the study. All the children in this study had pre-existing asthma at the time of their COVID-19 diagnosis.

Study findings

Children with asthma who were registered in the database before the pandemic formed one set of controls. Another set comprised children with COVID-19 without asthma.

The researchers found that cases were on average four years older than controls, at a median age of 14.6 years. All children with asthma, with or without COVID-19, were more likely to be Black and overweight than controls without asthma.

Almost 27% of children hospitalized with COVID-19 had asthma as compared to the 11% of children who were not admitted to the hospital. Furthermore, children with asthma who were hospitalized were also younger, with a median age of seven years as compared to 13 years in non-hospitalized COVID-19 children. About 40% of the hospitalized COVID-19 patients with a history of asthma were Black, whereas only 12% of the other cohort were of the same race.

Children with COVID-19 and a history of asthma had a higher incidence of presenting symptoms such as fever, fatigue, wheezing, breathlessness, chest pain, or vomiting. Additionally, up to 40% of these patients were treated with medication which is comparable to just over 1% of non-hospitalized children with COVID-19.

Interestingly, only one of seven cases required admission to the pediatric intensive care unit (PICU) as compared to eight of 19 children with COVID-19 but without asthma.

Asthma in children who developed COVID-19 was associated with a higher frequency of recent travel. These children were more likely to have wheezing, breathlessness, chest pain, and ageusia were hospitalized at almost four times the rate of controls without asthma and were more likely to be put on bronchodilators and corticosteroids.

About one in seven children developed a worsening of asthma just before or after their COVID-19 diagnosis. These children were more likely to be admitted than those without such acute asthma symptoms. Asthma was therefore a risk factor for hospitalization in children with COVID-19, irrespective of their body mass index (BMI) or duration from symptom onset. Asthma did not, however, worsen the clinical outcome.

Among asthmatic children, those who received a COVID-19 diagnosis were likely to have milder asthma. More specifically, almost 60% of cases had intermittent asthma as compared to 23% of those without a positive COVID-19 test. The median eosinophil counts were lower, the use of controller medications was less, and symptoms were better controlled in the asthma-COVID-19 group.

This group also had more older children with asthma, who had better asthma control than controls with asthma. Atopy was less frequent. Acute exacerbations were less by 0.43 event per year in this group.

Implications

This detailed study on children with asthma who develop COVID-19 finds that asthma is not a risk factor for COVID-19 in this age group, corroborating other studies. While asthma does increase the risk of hospitalization after a COVID-19 diagnosis by four times, the further clinical course was comparable to that of children without asthma.

Another finding was that COVID-19 does not appear to precipitate acute exacerbations of asthma, with more than eight of every ten children with asthma failing to show any symptoms of this illness during COVID-19. Those with clinical worsening formed a subset at higher risk for hospitalization and to receive systemic steroids as compared to other COVID-19 patients.

The BMI did not appear to show any increased risk for COVID-19 severity, other than that related to the presence of asthma, though the sample was too small to provide a conclusive answer. Black children remained at a higher risk for hospitalization after a COVID-19 diagnosis.

“With the advent of the Delta variant and current rise in COVID-19 cases, it will be important to conduct further, multi-center, individual-level, case-control or cohort studies of COVID-19 and asthma to better understand this evolving disease and its impact on children with asthma.”

*Important Notice

medRxiv publishes preliminary scientific reports that are not peer-reviewed and, therefore, should not be regarded as conclusive, guide clinical practice/health-related behavior, or treated as established information.

Written by

Dr. Liji Thomas

Dr. Liji Thomas is an OB-GYN, who graduated from the Government Medical College, University of Calicut, Kerala, in 2001. Liji practiced as a full-time consultant in obstetrics/gynecology in a private hospital for a few years following her graduation. She has counseled hundreds of patients facing issues from pregnancy-related problems and infertility, and has been in charge of over 2,000 deliveries, striving always to achieve a normal delivery rather than operative.