Are Allergies Protective Against Severe Covid19?

Allergic asthma is the most common type of asthma, affecting half of asthmatic adults and about 80% of asthmatic children. During the covid19 pandemic, my asthmatic patients have been concerned about the increased susceptibility they may have to the virus due to the increased mucus production and respiratory impairment associated with asthma. I think it is important to discern what the causal factors are for the asthma to really alleviate the concern because allergic asthma causes reduced ACE2 expression and non-atopic asthma does not.

ACE2 is a protein on the surface of many mucous lined parts of the body like the sinus passages, the lungs, heart, blood vessels, kidneys, liver and gastrointestinal tract. It is present in epithelial cells, which line certain tissues and create protective barriers. ACE2 is a vital element in a biochemical pathway that is critical to regulating processes such as blood pressure, wound healing and inflammation, called the renin-angiotensin-aldosterone system (RAAS) pathway and helps modulate the many activities of a protein called angiotensin II (ANG II) that increases blood pressure and inflammation.

Coronavirus uses the ACE2 receptors to infect the cells so it makes sense that the incidence and severity of COVID19 is higher in those with hypertension, diabetes and coronary heart disease. Evidence suggests that ACE2 may be higher in patients with hypertension, diabetes and coronary heart disease and lower in those with allergies. That seems like a good thing for those allergy sufferers, right?

While our world has been inundated with news of the pandemic the past two years, any silver lining or protection from the virus may be welcomed, and one may think that I am encouraging ignoring your allergies. This could not be farther from the truth. I think it is especially important to dig deeper into the cause of asthma symptoms, because allergic asthma can be very simple to treat and those with non-atopic asthma may be at higher risk for covid19 than those with allergic asthma and it is better to be informed. Also, as stated previously, ACE2 is vital in maintaining blood pressure, would healing, and reducing inflammation. If these levels are drastically declined in allergic conditions, that means that these people are open to a whole host of more serious problems long-term than this pandemic.

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