Asthma control after recovery from mild to moderate COVID-19: from Omicron BA.2 to XBB- from a cohort in a university hospital in Hong Kong.

Background: At the time of Omicron BA.2 outbreak, it was shown that mild to moderate COVID-19 was associated with worsening of asthma control after recovery. Whether the same phenomenon was also observed at a later phase of COVID-19 pandemic by other variants have not been reported.

Methods: We conducted a follow-up study on patients with asthma who received clinical care in Queen Mary Hospital. The patients were first recruited in the study entitled "Worsening of asthma control after recovery from mild to moderate COVID-19 in patients from Hong Kong". The primary outcome was the asthma control test (ACT) score difference among the patients who never had COVID-19 (no COVID-19 group), patients who had COVID-19 diagnosed in the initial study (past COVID-19 group) and patients who had COVID-19 diagnosed in the follow-up period (new COVID-19 group) of the current study.

Results: 189 patients were included. The change of ACT score from the last visit in the previous study to the last follow-up visit in current study was - 0.34 ± 3.7 in the no COVID-19 group, -0.0 ± 5.0 in the past COVID-19 group and - 0.17 ± 4.5 in the new COVID-19 group (p = 0.94). There were 10 (24.4%), 24 (25.5%) and 12 (22.2%) patients in the no COVID-19, past COVID-19 and new COVID-19 group who had worsening of asthma control by an increase in ACT score ≥ 3 from the last visit in the previous study to the last follow-up visit in current study (p = 0.90).

Conclusion: Patients who had COVID-19 in 2023 with Omicron XBB as the dominant strain did not have worsening of asthma control seen in previous study done in 2022 with Omicron BA.2 as the circulating strain. Patients who had worsening of asthma control after COVID-19 in 2022 had subsequent improvement of asthma control with longer follow-up interval.