Asthma and severe acute respiratory syndrome coronavirus 2019: current evidence and knowledge gaps / SM. Assaf, SP. Tarasevych, Z. Diamant, NA. Hanania,
Assaf, Sara M Section of Pulmonary and Critical Care Medicine, University of New Mexico, Albuquerque, New Mexico, USA. Tarasevych, Svitlana P Department of Respiratory Medicine, Zaans Medical Center, Zaandam, The Netherlands. Diamant, Zuzana Department of Respiratory Medicine & Allergology, Institute for Clinical Science, Skane University Hospital, Lund University, Lund, Sweden. Department of Microbiology Immunology & Transplantation, KU Leuven, Catholic University of Leuven, Belgium. Department of Respiratory Medicine, First Faculty of Medicine, Charles University and Thomayer Hospital, Prague, Czech Republic. Department of Clin Pharm & Pharmacol, Univ Groningen, Univ Med Ctr, Groningen, Groningen, The Netherlands. Hanania, Nicola A Section of Pulmonary and Critical Care Medicine, Baylor College of Medicine, Houston, Texas, USA.
PURPOSE OF REVIEW: Although respiratory viruses are common triggers of asthma exacerbation, it is unknown whether this also applies to infection with SARS-CoV-2. Indeed, patients with asthma and allergy appear underrepresented in large reports of COVID-19 cases worldwide. In this review, we evaluate existing literature on this topic and potential underlying mechanisms for any interrelationship between asthma and COVID-19. RECENT FINDINGS: Data from several preclinical and clinical reports suggest a lower susceptibility for COVID-19 in patients with underlying type 2 airway inflammation including asthma that may be related to a reduced expression of ACE2 and TMPRSS2 receptors for SARS-CoV-2. Corticosteroids further decrease expression of the ACE2 and TMPRSS2 receptors, hence may also have a protective effect against infection with SARS-CoV-2. In addition, some studies suggest that the reported improvement in asthma control and a reduction in asthma exacerbations during the COVID-19 pandemic may be related to improvement in adherence to controller therapy and reduced exposure to triggers, such as other respiratory viruses and air pollutants. Recent data point towards differential susceptibility for COVID-19 among asthma patients based on their phenotype and/or endotype. On the basis of existing evidence, continuation with controller therapies is recommended for all patients with asthma. For patients with severe uncontrolled asthma infected by SARS-CoV-2, adjustment of controllers and biologics should be based on a multidisciplinary decision. SUMMARY: Underrepresentation of SARS-CoV-2-infected patients with asthma and related allergic diseases may be based on potentially protective underlying mechanisms, such as type 2 airway inflammation, downregulation of ACE2/TMPRSS2 receptors, reduced exposures to triggers and improved adherence to controller medications. Although it is imperative that control should be maintained and asthma medications be continued in all patients, management of patients with severe uncontrolled asthma infected by SARS-CoV-2 including adjustment of controllers and biologics should be discussed on an individual basis.