- At the beginning of the pandemic, it was thought that people with asthma had a higher risk of severe outcomes
- New research, however, found that asthma doesn't raise the risk of being hospitalised due to Covid-19
- This might be because people with allergic asthma have 'less area for the virus to attach to'
New research may have people with asthma breathing a little easier: Doctors found the airway disease doesn't raise the risk of being hospitalised due to Covid-19.
The researchers also noted that people with asthma weren't more likely than people without it to need a ventilator to help them breathe.
"A lot of people with asthma think they have a predisposition to severe Covid, and they worry a lot about going out. They should take precautions like using their masks, but they may not need to worry so much," said study author Dr Fernando Holguin. He's director of the Asthma Clinical and Research Program at the University of Colorado Anschutz Medical Campus, in Aurora.
Holguin said the proportion of hospitalised Covid-19 patients with asthma was around 6%.
Higher risk of hospitalisation
"For most places, that's an asthma prevalence that is at or lower than the asthma prevalence in the general population. To compare, with influenza [flu], we typically see about a quarter of those in the hospital have asthma," he said.
When the pandemic first began, the US Centers for Disease Control and Prevention suggested that people with asthma had a higher risk of hospitalisation and other severe outcomes. People with asthma do have a significantly higher risk of complications with flu, another viral infection.
In the new study, the researchers reviewed 15 studies on Covid-19 infections to see how many people hospitalised had asthma. They also looked at more than 400 patients treated for Covid-19 at the University of Colorado Hospital, to see whether the rates of ventilator use were different in people with asthma.
"The message from our study is not to be cavalier about Covid, but individuals with asthma won't do worse than people without it," Holguin said.
Other research also points to the same conclusion. A June study in the Journal of Allergy and Clinical Immunology of more than 1 500 people (220 with asthma) who had Covid-19 found that people with asthma weren't more likely to be hospitalised. They also didn't have a higher risk of death.
Too soon to know
Holguin said the researchers have a theory as to why Covid-19 infections don't seem to lead to worse outcomes in people with asthma.
"Allergic asthma is associated with lower numbers of ACE2 receptors. These are the receptors the virus uses to anchor itself to cells," he said. That means people with allergic asthma may have less area for the virus to attach to. Holguin added that people who use inhaled corticosteroids (an asthma treatment) also have fewer ACE2 receptors.
The new findings were published on 31 August in the Annals of the American Thoracic Society.
Dr Charles Fishman, a pulmonologist with the NewYork-Presbyterian Medical Group Westchester, in New York City, said, "This study's findings are consistent with what we've seen clinically. The original concern was that since people with asthma are disproportionately hospitalised with flu, that they might also have bad outcomes with coronavirus. But that doesn't seem to be the case with coronavirus."
Fishman said it's probably too soon to know why people with asthma are faring better than expected.
"There so much that's still unknown. It's important in drawing conclusions that we really rely on good science," he added.
In the meantime, like Holguin, he advised, "People with asthma should exercise the exact same caution as people without asthma. They don't need to be increasingly concerned, but should have a healthy respect for what this virus can do. Until a vaccine is available and the population is fully protected, continue to do those things that protect you from the virus [such as wearing a mask, washing your hands frequently and keeping safe distances from others]."
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