Patients with pre-existing allergic rhinitis face a 1.75 times higher risk of developing a new asthma diagnosis after contracting COVID-19, according to a study published in Nature Communications.
COVID-19 and Post-Infection Asthma Risks
The study utilized data from the Korea Disease Control and Prevention Agency and National Health Insurance Service cohort, tracking approximately 3,987,000 COVID-19 patients with no prior history of asthma.
The investigators matched the patient groups 1-to-1 based on age, sex, residential area, income level, underlying conditions, and medication use, resulting in a final analysis pool of approximately 1.56 million individuals in each group. Among confirmed COVID-19 patients who held prior allergic or upper respiratory diagnoses, 3,808 individuals were newly diagnosed with asthma, compared to 2,300 individuals in the control group. This corresponds to an incidence rate of 3.55 per 1,000 person-years for the disease group versus 2.13 for the controls, marking a 66% overall increase in relative risk, according to the published data.
Impact of Specific Allergic and Upper Respiratory Conditions
When breaking down the data by specific disease types, every evaluated condition showed a distinct association with an increased risk of subsequent asthma. According to the findings, patients who suffered from allergic rhinitis prior to COVID-19 infection faced a 1.75 times higher risk of a new asthma diagnosis compared to those without the condition.
Other conditions demonstrated even higher risk ratios in the matched cohort:
- Atopic dermatitis: 1.84 times higher risk.
- Chronic rhinosinusitis: 2.04 times higher risk.
- Food allergies: 2.81 times higher risk.
However, the research team emphasized that the food allergy results require cautious interpretation because only 22 actual cases of new asthma diagnoses occurred within that specific patient subgroup.
Cumulative Disease Burden and Symptom Persistence
The risk of developing asthma scaled upward as patients accumulated multiple overlapping conditions prior to contracting COVID-19. According to the study, individuals who had a single pre-existing allergic or upper respiratory disease faced an asthma risk 1.58 times higher than the control group. For patients harboring two or more concurrent conditions, that risk escalated to 2.44 times higher.
To evaluate disease severity indirectly, the researchers examined pre-infection systemic steroid usage. Patients who used systemic steroids at or below the average level showed an asthma risk 1.53 times higher than controls, while those exceeding the average usage level faced a 1.96 times higher risk. The study authors noted that this correlation likely reflects the baseline activity or severity of the patient’s pre-existing condition rather than the steroids directly causing asthma.
Even after adjusting for pre-infection healthcare utilization rates to account for the possibility that allergic patients visit clinics more frequently and thus receive diagnoses earlier, the adjusted hazard ratio remained elevated at 1.37. Nevertheless, because the study relied on observational data, the research team cautioned that pre-existing conditions cannot be definitively proven to directly cause post-COVID asthma.