Asthma and COVID-19: Making Sense of Data

July 31, 2020 | Asthma, Clinical Science Research

For the past three years, I have written about updates in peanut desensitization during the month of July.  However, I have received questions about the risks of COVID-19 for those with asthma over the past month. So, this month’s blog will –for the 3rd month this year—be devoted to the medical condition affecting all of us in so many ways.

At present, the CDC states that people with moderate to severe asthma might be at risk for severe illness from COVID-19.  This statement contrasts with their list of medical conditions that do increase the risk of severe illness from COVID-19:  cancer; chronic kidney disease; COPD (i.e. emphysema); immunocompromised state from solid organ transplant; obesity—defined as a body mass index > 30; serious heart conditions such as coronary artery disease and congestive heart failure; sickle cell disease and type 2 diabetes.

For those with asthma, the CDC has a list of actions to take:  Among these is to continue daily controller medications…including steroid inhalers.

The American Academy of Allergy, Asthma and Immunology has the following patient education statements about asthma and COVID-19 that have been posted since June 22nd.

  • Currently, there is no evidence of increased infections rates in those with asthma.
  • Although the CDC states that those with moderate to severe asthma could be at greater risk for severe COVID-19, there are no published data to support this.
  • Patients are to continue their daily controller medications. Data suggesting that steroids could increase shedding of the SARS-CoV-2 virus (i.e. the COVID-19 virus) comes from treating those hospitalized with intravenous steroids, but patients with asthma were not studied.

The Academy’s post states that only one report suggests that asthma may increase the risk of hospitalization from COVID-19 in the age group 18-49.  It also cites data from New York that asthma was under-represented in those who died from COVID-19.

Locally, a study from Northwestern University Medical Center was published late last month in the Journal of Allergy and Clinical Immunology that looked at the prevalence of asthma among 1,526 patients diagnosed with COVID-19.  Of these patients, 220 (14%) were considered to have a history of asthma.  From the data, the authors concluded that (a) asthma was not associated with an increased risk of hospitalization for COVID-19, and (b) use of inhaled steroids did not increase the risk of hospitalization.

During this year, the observations about asthma affecting COVID-19 have varied.  The initial case series reports from China and Italy in the Journal of Allergy and Clinical Immunology were of asthma prevalence in hospitalized patients of 0.9% and ~1.9%, respectively, when the estimated prevalence of asthma in their local general populations is ~6%.   However, asthma prevalence among those hospitalized in this country has since been found to be higher in both New York (9% of 5,700 patients with the estimated local asthma prevalence of 10.1%. JAMA; Apr. 22], 14 states [17% of 1,482 patients; Morbidity and Mortality Weekly Report; Apr. 17] and Georgia [10.5% of 305 patients; Morbidity and Mortality Weekly Report; May 8].  The national asthma prevalence was considered in 2018 to be 7.7% of adults and 8.4% of children [; last reviewed Jan. 2020].  These USA hospital percentages are comparable to the prevalence of asthma seen in the UK, where 14% of 16,749 COVID-19 hospitalizations had a history of asthma [Int. Arch. Allergy Immunol.; June 9].

Having asthma seems to be no less likely, and no markedly more likely, to lead to a COVID-19 hospitalization.  What the UK data on COVID-19 mortality does show, as published earlier this month, is that severe asthma is associated with a high risk of death from COVID-19 [Nature; July 8].  Severe asthma was defined by the researchers in the UK as prior and recent use of an oral—not inhaled—steroid.

Basic science observations this year, though, are encouraging for most individuals with asthma to avoid complications if infected with SARS-CoV-2.  These include the following:

  1. Inhaled steroid use was associated with lower gene expression of ACE2 receptor (i.e. the cell receptor that binds the virus) in sputum from asthma patients and was similar to healthy controls [Am J Respir Crit Care Med; Apr 29].
  2. There was no difference in the levels of ACE2 receptor and two other molecules associated with COVID-19 infection between 88 healthy volunteers, 125 patients with mild-moderate asthma and 143 patients with severe asthma [J Allergy Clin Immunol; July].
  3. ACE2 receptor levels are lower in individuals with high allergic reactivities but not in those with non-allergic asthma [J Allergy Clin Immunol; April 22]
  4. The allergy antibody class IgE reduces the body’s production of alpha-interferon, which contributes to the early inflammation during an infection [Allergy; May 25]

Children do have less of the ACE2 receptor when compared to adults. However, a natural question arises: Is the lower prevalence of COVID-19 infection in children with asthma due to being away from school and avoiding transmission of respiratory viruses?  A pulmonary specialist from London named Richard Chavasse wrote this month in the British Medical Journal that admissions for acute asthma decreased from 3-5 per day to 1-2 per week after lockdowns occurred.  He further wrote:

Children must not be sidelined as we rebuild and redesign systems for the future….The importance of school education is undeniable but we should reflect on the school environment and the effects (positive and negative) it has on children’s health.”

We all want to return to the time before COVID-19 and to have a risk-free environment.  I think we need to reframe our thinking as we look at the present and into the future.  The goal should be to have instead a careless-free environment.  Until the safe and effective laboratory vaccine is developed, the already safe and effective ‘behavioral vaccine’—the term coined by health psychologist Susan Michie of University College London and that I referenced in my March blog—must be used in public places and in households.  The prevailing observational and experimental scientific data lean toward the use in public of a mask–as uncomfortable as it is to wear–based largely on the discovery that presymptomatic individuals begin to shed virus in respiratory droplets 2 to 3 days before they start to have symptoms.  Any additional environmental precautions depend on an analysis of the individual’s history of asthma exacerbations and recent lung function.

There is room for hope amidst the upheaval and uncertainty that this pandemic hath wrought.  Either a highly effective therapeutic and/or a vaccine is quite likely to be available in the next 6 to 9 months.  The issue is crossing that bridge of time.  Those of us who are younger than 80 have no recollection of the rationing that took place for 3 ½ years during World War 2.  Those of us who are younger than 85 have not experienced unemployment to the level we have seen the past four months.  With determination, patience and collaboration over the next 6 to 9 months, as the citizens of our country had in the 1930s and 1940s, we will also cross this bridge successfully.

Dr. Klein