While certain health conditions have been linked to an increased risk of complications with COVID-19, Rutgers University researchers say asthma is not among them.
"Older age and conditions such as heart disease, high blood pressure, obstructive pulmonary disease, diabetes, and obesity are reported risk factors for the development and progression of COVID-19," explained Dr. Reynold A. Panettieri Jr., a pulmonary critical care physician and director of the Rutgers Institute for Translational Medicine and Science .
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"However, people with asthma – even those with diminished lung function who are being treated to manage asthmatic inflammation – seem to be no worse affected by SARS-CoV-2 than a non-asthmatic."
The reasons why are still unclear, he added. It could be physiological or an unexpected effect of the steroid medications used to treat asthma, a chronic condition that affects the lungs and requires ongoing management.
An asthma attack occurs when the lungs become inflamed, constricting one's airway. Asthma symptoms – difficulty breathing, wheezing, coughing and tightness in the chest – are typically triggered by allergens or irritants that enter the lungs.
Early on in the pandemic, people with asthma were thought to be more susceptible to severe cases of COVID-19, like others with chronic conditions. Much of the actual data though tells a different story though.
One analysis that looked at more than 1,500 people found that COVID-19 patients with asthma weren't any more likely to be hospitalized than those patients without asthma.
Panettieri and his co-authors explore the possible reasons why in an editorial in The Journal of Allergy and Clinical Immunology .
One factor they suggest is that people with asthma have been extra vigilant about practicing social distancing and following other precautions during the COVID-19 pandemic. According to Panettieri and his colleagues, there is also evidence that people are adhering to their treatment regimen more closely to prevent flare-ups
Less time outside and around other people could also be reducing their exposure to seasonal triggers and other respiratory viruses, not just SARS-CoV-2, improving their overall health, they added.
The inhaled steroids used to treat asthma could also be reducing the virus' ability to spread throughout the body by decreasing the expression of the angiotensin-converting enzyme – or ACE2. This enzyme has been shown to be how the novel coronavirus enters cells.
Another factor could be age, the researchers said. From the beginning of the pandemic, older people have been considered the most vulnerable to severe COVID-19.
Panettieri and his colleagues point out that most asthma sufferers are younger than those with other high risk conditions. Older people with severe asthma and those with multiple health conditions may still be at heightened risk however.
According to the Rutgers researchers, other studies suggest the opposite – that the steroids actually worsen the body's inflammatory response in a SARS-CoV-2 infection.
Before any definite conclusions can be made they stressed that more research is needed to identify the characteristics of asthma patients who do develop COVID-19 and determine whether the medications they take increase or decrease their risks for severe disease.
Other asthma experts agree that the link between SARS-CoV-2 and asthma is more complex than expected and that more research is needed. One important question that needs to be addressed is whether certain types of asthma puts a person at greater risk than the others.
In one study, patients with non-allergic asthma, the type triggered by exercise, stress and cold weather not allergens, appeared more vulnerable, not less. The theory is that in these patients, ACE2 expression is increased, while in patients with allergic asthma the enzyme levels are decreased.
The one thing that is absolutely clear: All researchers are saying there are more questions that need answering to truly understand how asthma and the virus interact.