Woman using asthma inhaler
While Covid-19 infections can literally ravage every organ system, the respiratory tract has been its primary target. The acute viral inflammation of the airway and lungs has led to millions worldwide requiring aggressive medical management, oftentimes leading to placement on a mechanical ventilator. This intervention can lead to other complications, including brain, heart, and kidney damage. Once on the ventilator, many will not regain enough strength to breathe on their own. Respiratory failure is one of the most common causes of death due to Covid-19.
Patients with a history of lung disease, especially asthma, have been considered to be at much higher risk of respiratory complications due to Covid-19, as having a diagnosis asthma leads to chronic as well as acute inflammation of the small airways (bronchi and alveoli) of the respiratory tract. Over 25 million Americans, including children, suffer from asthma. The disease leads to airway narrowing due to inflammation, leading to coughing, wheezing, and occasionally respiratory distress. Historically, individuals with asthma are at much higher risk for developing bronchitis or pneumonia from even mild respiratory illnesses compared to the non-asthmatic population.
Representation of the lungs with the bronchial tree. In the upper left, a healthy bronchiole, below, ... [+]
Several recent studies found that having a history of asthma does not lead to increased risk of severe Covid-19 infection or death due to Covid-19. In a study based at the Massachusetts General Hospital in Boston, investigators compared 80 asthmatics admitted to the hospital with acute SARS-CoV-2 (Covid-19) infections to a similar number of age-matched patients admitted for Covid-19 infections with no history of asthma. Their work, published in the January 2021 issue of The Journal of Allergy and Clinical Immunology, found that relatively fewer asthmatics required ICU admission or mechanical ventilation. Asthmatics also had a slightly lower risk of death compared to the non-asthmatic group. The results were somewhat surprising. One explanation the authors suggest is that the higher risk severity for Covid-19-related pulmonary complications is likely more prevalent in patients with chronic obstructive pulmonary disease (COPD), such as emphysema or chronic bronchitis, than in those with asthma. In addition, patients with asthma are more likely to be utilizing inhaled bronchodilators and anti-inflammatory inhalers with steroids, possibly preventing some of the acute inflammation of the airways from SARS-CoV-2 infections.
Doctor holding oxygen ambu bag over patient given oxygen to patient by endotracheal tube in ICU.
Another study, published in the January 2021 issue of the American Journal of Respiratory and Critical Care Medicine reviewed 147 studies of Covid-19 patients with and without diagnosis of asthma. They found that patients with a history of asthma had no increased risk of severity of or morbidity from Covid-19 infections. A study published in the Journal of Asthma in February 2021 reviewed 57 studies, which included a total of over 500,000 people. They found that people with asthma actually had a 14% lower likelihood of developing Covid-19 infections. In those who did develop Covid-19 infections, asthmatics did not show an increased risk of death compared to those with no history of asthma.
The combination of increased vigilance and concern for respiratory complications, combined with chronic use of inhaled corticosteroids, often used as therapeutics for acute respiratory inflammatory processes such as Covid-19, may, in part, explain the protective mitigations for asthmatic individuals. The growing body of evidence should be reassuring to asthmatics. Continued mitigating measures, including mask wearing, vaccination, physical distancing, and maintenance of preventive and therapeutic interventions to minimize asthma exacerbations remains paramount.
