'Long COVID' Chronic Cough Patients, Half Have Asthmatic Cough

Professor Song Woo-jung's Team at Seoul Asan Hospital

Cough is a representative symptom of 'Long COVID,' which refers to long-term aftereffects following COVID-19 infection. A study by domestic medical professionals has drawn attention by revealing that nearly half of these chronic cough patients are asthma-related cough patients.

Professor Woojung Song of the Department of Allergy at Seoul Asan Medical Center and Professor Soyoung Park's team from the Department of Respiratory Allergy at Chung-Ang University Gwangmyeong Hospital announced on the 13th that 44.7% of Long COVID chronic cough patients were identified as having asthma-related cough.

Professor Song Woo-jung, Department of Allergy, Asan Medical Center, Seoul (left), Professor Park So-young, Department of Respiratory Allergy, Chung-Ang University Gwangmyeong Hospital.

Asthma-related cough is one of the main causes of chronic cough and, as the name suggests, is a cough caused by asthma. It is characterized by a cough that is more prominent than shortness of breath or wheezing. It is difficult to diagnose with simple pulmonary function tests alone.

The research team conducted a comparative analysis of the clinical characteristics and initial treatment responses of 121 patients who visited the hospital with Long COVID chronic cough and 100 patients with general chronic cough from March to November last year. Among the Long COVID chronic cough patients, 55 were analyzed prospectively and 66 retrospectively.

First, to analyze the causes of chronic cough, they performed a fractional exhaled nitric oxide (FeNO) test, which measures the degree of bronchial inflammation. The results showed that about 44.7% of Long COVID chronic cough patients and about 22.7% of general chronic cough patients had asthma-related cough.

Next, patients were treated according to existing chronic cough treatment guidelines. Among the 42 Long COVID chronic cough patients analyzed prospectively, who responded to the Leicester Cough Questionnaire (LCQ), a self-assessment tool for cough status, after an average of 35 days, 83% showed significant symptom improvement. After treatment, Long COVID chronic cough patients experienced a reduction in accompanying symptoms such as chronic fatigue, sleep disorders, and headaches, and their quality of life score (EQ-VAS) improved significantly from an average of 63 points to 74 points.

Furthermore, there were no significant differences in radiological examination results such as chest X-rays and computed tomography (CT) scans between Long COVID chronic cough patients and general chronic cough patients.

Professor Woojung Song stated, "Asthma symptoms tend to worsen after cold virus infections, and it appears that asthma latent after COVID-19 virus infection is more easily manifested." He added, "This study provides initial evidence that applying existing chronic cough treatment guidelines is effective." He continued, "However, about 20% of patients who do not respond well to existing chronic cough treatments still remain, and it is not yet known whether the favorable initial treatment response continues long-term, so further research is underway."

The results of this study were recently published in the English academic journal Allergy, Asthma & Immunology Research (IF=5.096), published by the Korean Academy of Asthma, Allergy and Clinical Immunology.