Could Asthma Protect Us From COVID-19?

Asthma was initially listed as high risk for COVID-19. In fact, the CDC still lists moderate to severe asthma as high risk.¹ That said, there is evidence out there that may suggest otherwise. And this has piqued the interest of researchers. So, is it possible something about asthma may actually protect us from COVID-19?

The state of New York was one of the first to be hit by the virus. By April of 2020, the state released data listing the top 10 diseases most diagnosed among those who died of COVID-19. Missing from this list was asthma. It was revealed that less than five percent of those deaths were asthmatics. Doctors also started observing how few asthmatics with COVID they were caring for.²

This piqued my interest. Apparently, it piqued the interest of researchers too. They have been studying this quite diligently and have even conducted some studies to explain why asthma might keep us safe from the SARS-CoV-2 virus, the virus that causes COVID-19.

Overview of the asthma and COVID-19 studies

Asthmatics have fewer ACE-2 receptors

Receptors are important structures on cell walls. They act as keys and only allow substances that can bind with these receptors into the cell. This assures only healthy substances can enter cells. But, sometimes harmful substances can do this, such as viruses. Lung cells contain ACE-2 (Angiotensin Converting Enzyme 2) receptors, and researchers think this is how the SARS-CoV-2 virus enters lung cells. Asthmatics may produce fewer of these receptors, which makes asthmatics less likely to develop COVID-19.^3-5

Asthmatics are more careful with mitigation procedures

Asthmatics understand they are at higher risk and therefore are more careful. This hypothesis postulates that those with asthma are likely to stay home and avoid contact with other people. They may also be more likely to wear their masks when out in public. This, therefore, would make asthmatics less likely to become infected with SARS-COV-2. Some researchers have already expressed doubt about this hypothesis. Their reasoning is that asthma rates among hospitalized COVID-19 patients were low even before mitigation policies were set in place.⁵

Corticosteroids may inhibit the impact of the SARS-COV-2 virus

Corticosteroids are used to reduce airway inflammation. Although they may also "inhibit ACE-2 expression in asthma." And in this way, they may prevent the virus from entering cells.^5,6

Antihistamines may prevent SARS-COV-2 from entering cells

Many asthmatics have allergies and antihistamines like diphenhydramine (Benadryl) are often used to treat allergy symptoms. These medicines may prevent the SARS-CoV-2 virus from entering cells.⁷

Chronic airway inflammation may prove protective against the virus

Asthmatics already have some degree of underlying airway inflammation and this may prevent further inflammation in response to SARS-CoV-2. In this sense, it may make asthmatics "immune" to the inflammatory response responsible for severe COVID-19. So, inflammation may prevent a mild case of COVID-19 from becoming more severe.⁵

Hypersecretion may prevent the virus from getting deep into the lungs

Asthmatic airways tend to produce abnormal amounts of sputum. This is known as "hypersecretion." This sputum traps and kills viruses, carrying them up to the upper airways to be swallowed or spit up. Having extra sputum may prevent SARS-CoV-2 from getting deeper into your lungs. And in this way, this "hypersecretion" may also prevent mild cases of COVID-19 from becoming more severe.⁵

Other hypotheses

Fear of the pandemic may ensure asthmatics are more compliant with their treatment regimen, making them healthier overall, and this may make them less likely to develop severe COVID-19. Another hypothesis suggests asthmatics are younger in age and COVID-19 is mainly a disease of the elderly population. So, this may explain the lower rates of asthma in hospitalized COVID-19 patients.

Asthmatics tend to have an elevated inflammatory response. They have more white blood cells in their lungs than normal, which are the same cells that fight infections, such as viral infections. So, this overactive immune response may prove effective in protecting asthmatic lungs from the effects of SARS-CoV-2.⁸

What to make of this?

Traditionally, respiratory viruses are known for triggering asthma. In previous various pandemics, asthmatics were highly likely to be hospitalized. They were at an increased risk of having asthma exacerbations while hospitalized and were overall increasingly likely to catch these viruses and suffer from the diseases they caused.⁵

This does not seem to be the case with COVID-19. Researchers have reviewed the data and they have completed various studies confirming that people with pre-existing asthma are less likely to get COVID-19. They have confirmed that asthma does NOT increase your risk of getting COVID-19. It may, in fact, prevent mild cases of COVID-19 from becoming more severe.^4,5,8

What is the explanation for this? Which of the above hypotheses will hold true, if any? As the results come in we will be sure to keep you posted.