New research from the University of Wisconsin-Madison suggests that contrary to government guidelines, asthma may not put a person at increased risk for severe COVID-19, but may, in fact, offer some protection against it.
The findings run counter to what has been conventional wisdom, and underscore just how much scientists have to learn about the new disease that has killed more than 230,000 people worldwide since December, 62,500 in the U.S.
The U.S. Centers for Disease Control and Prevention still lists severe asthma as one of the underlying medical conditions that put a person at greater risk for severe illness from COVID-19.
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However, the guidance has not matched early studies from China. Those studies showed that COVID-19 patients did not seem to include an especially high proportion of asthmatics, said Daniel Jackson, associate professor of pediatrics and medicine at UW School of Medicine and Public Health.
“This surprised all of us in asthma research,” said Jackson, lead investigator of the new study, which appears online in The Journal of Allergy and Clinical Immunology.
Other respiratory infections such as the H1N1 swine flu, rhinoviruses and parainfluenza do put people with respiratory allergies and allergic asthma at higher risk of severe illness. For example, 30% of those hospitalized during the swine flu epidemic had asthma.
Results from China found the proportion of COVID-19 patients with asthma to be about 8 to 9% — about equal to the proportion of the general population who have asthma.
Jackson and his colleagues focused on levels of ACE2, a gene that plays a critical role in COVID-19. ACE2 makes a receptor, also called ACE2, which is the doorway through which the new coronavirus enters.
Coronavirus cells use a protein called SPIKE to attach themselves to healthy cells. The SPIKE protein and ACE2 receptor form a bond, which allows viral cells to grab onto healthy cells and invade them.
Diseases such as hypertension and obesity are accompanied by increased production of ACE2. For the new coronavirus, a boost in ACE2 would be like a welcome mat.
But that is not what the UW researchers found. They tested ACE2 levels in three groups: children with higher levels of allergy and asthma; adults with allergy alone; and adults with mild asthma.
Using swabs from the nasal and lower airways of patients, the scientists found that all three groups had reduced levels of ACE2, leaving the new coronaviruses with less of an opportunity to gain a foothold.
Jackson stressed that there are likely other factors beyond ACE2 levels that influence our response to COVID-19. He said the National Institutes of Health is launching a study of various factors that may affect the risk a person faces from the new coronavirus.
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