As the novel coronavirus 2019 (COVID-19) spread, people with asthma grew worried. COVID-19 is a respiratory virus. Asthma is a respiratory condition. Then the US Centers for Disease Control and Prevention released a list in March that included asthma as an underlying medical condition that put individuals at increased risk for severe illness from COVID-19. However, a few months later that precaution has been refined. So what is the latest information? And why are some types of asthma sufferers more at risk than others?
Asthma and COVID-19
Asthma rates are on the rise. No one is certain why. The “clean-house syndrome” may be a culprit. This theory suggests that our obsession with clean environments has perversely led to an increase in allergies and other illnesses. Indeed, the polio epidemic of the 20th century was partly due to cleaner living conditions; delaying an illness that was benign in infants but horrific in older children and adults. One 2014 study suggested that infants exposed to dust mites, pet dander, and other allergens were less likely to develop allergies or asthma as toddlers. Cleaning products themselves often increase the risk for asthma attacks. Other possible asthma culprits include energy safe homes and offices that limit the amount of fresh air, raising air pollution and airborne pollen. In the US alone, over 25 million people have asthma; around eight percent of the population.
Because COVID-19 is a novel virus, information about it is ever evolving. We now know that the virus affects other organs–not just the lungs. Still, for asthma sufferers, lung damage is a primary concern. Unfortunately, because asthma is less prevalent in China, where the outbreak began, it wasn’t studied as a hospitalization factor. An April 2020 examination of over 1,000 admitted COVID-19 patients in the U.S. uncovered several things. First, while asthma was present in around 17% of the admitted patients, the number rose to over 25% among those ages 20 to 49 years.
The study also determined that people with a history of asthma were not more likely to be hospitalized with COVID-19. Neither did they experience an increased rate of acute respiratory distress syndrome, where fluid leaks into the lungs. However, obese patients with asthma had a markedly worse outcome than those with just one of the two conditions. Further, asthma patients who were intubated had a significantly longer intubation time.
Evidence is clear
A recent study is even more specific. In a pre-proof paper published online in The Journal of Allergy and Clinical Immunology on June 6, 2020, researchers using UK Biobank looked at nearly 700 people with severe COVID-19 (out of nearly 500,000 data sets in the biobank). They saw clear evidence for a higher risk of severe COVID-19 among participants with asthma. Then they went one step further. They discovered that severe outcomes were being solely driven by the significant association of nonallergic asthma. Allergic asthma had no statistically significant association with severe COVID-19 risk.
Allergic asthma is triggered by the same sorts of things that trigger allergies –– pollen, pet dander, dust mites. Non-allergic can be triggered by stress, hot or cold weather and, most commonly, exercise (known as exercise-induced bronchoconstriction.) On July 17, 2020, the CDC dropped asthma from its list of underlying medical conditions that “are at increased risk of severe illness from COVID-19.” On that list are conditions including cancer, obesity, and Type 2 diabetes mellitus. Asthma, along with high blood pressure and pregnancy, are now on a list of conditions that “might be at an increased risk for severe illness from COVID-19.” It’s an important change. To clarify: asthma alone is not necessarily indicative of a higher risk factor for COVID-19. However, patients with more severe non-allergic asthma and co-morbidities including obesity and type 2 diabetes are at higher risk. This is probably due to the systemic inflammatory effect of obesity and type 2 diabetes during times of stress and illness.
While asthma sufferers need to continue their treatments and avoid triggers, for many the news means they can breathe a little easier.
- Evidence used to update the list of underlying medical conditions that increase a person’s risk of severe illness from COVID-19
- Effects of early life exposure to allergens and bacteria on recurrent wheeze and atopy in urban children
- Asthma data: Centers for Disease Control and Prevention
- Asthma prolongs intubation in COVID-19
- Association of asthma and its genetic predisposition with the risk of severe COVID-19
- CDC: People with Certain Medical Conditions
John Bankston is a published author of over 150 nonfiction books for children and young adults including biographies of Jonas Salk, Gerhard Domak, and Frederick Banting.