Asthma and COVID-19: a controversial relationship.

Area of Science:

• Immunology
• Epidemiology
• Respiratory Medicine

Background:

• Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection, causing COVID-19, presents diverse clinical outcomes influenced by patient immune responses.
• A cytokine storm, characterized by excessive inflammatory mediators, can arise from an ineffective T helper (Th)-1 response, leading to tissue damage.
• Asthma patients exhibit variable COVID-19 outcomes due to disease heterogeneity, with Th2 responses potentially mitigating cytokine storms, while severe neutrophilic asthma is linked to poor outcomes.

Purpose of the Study:

• To explore the complex interplay between SARS-CoV-2 infection, immune responses, and asthma patient outcomes.
• To investigate the impact of COVID-19 lockdown measures on asthma and acute respiratory infection (ARI) epidemiology.
• To understand the relationship between social distancing, ARIs, and asthma incidence.

Main Methods:

• Review of clinical manifestations and immune responses in SARS-CoV-2 infected individuals, focusing on asthma patients.
• Analysis of asthma and ARI incidence data in relation to COVID-19 lockdown stringency in Mexican states.
• Comparison of pre- and post-lockdown epidemiological trends for asthma and other diseases.

Main Results:

• The T2 response in allergic asthma may prevent cytokine storms in COVID-19, while IL-13 can reduce SARS-CoV-2 entry by downregulating ACE2 receptors.
• Severe neutrophilic asthma is associated with adverse COVID-19 outcomes.
• A significant decrease in asthma and ARI cases was observed during the COVID-19 lockdown, with a notable link between social distancing and reduced incidence.
• Unlike other diseases, asthma and ARI cases did not fully recover to pre-pandemic levels post-lockdown, with slight increases upon return to in-person activities.

Conclusions:

• Asthma patient outcomes during the COVID-19 pandemic are multifactorial, influenced by specific immune responses and disease severity.
• COVID-19 lockdown measures, particularly school closures and social distancing, were strongly associated with a reduction in asthma and acute respiratory infection cases.
• Acute respiratory infections appear intrinsically linked to asthma exacerbations and incidence, highlighting the importance of infection control measures.