Lung Yi Mak

Evidence remains scant regarding post-acute sequelae associated with hospitalised COVID-19 re-infection versus hospitalised first-time infection, especially during the Omicron dominant period. Hospitalised COVID-19 re-infection was associated with a significantly higher risk of post-acute all-cause mortality, all-cause hospital readmission and attendance to emergency departments, compared with hospitalised first-time infection.

Contributors The authors declare they have participated in the preparation of the manuscript and have seen and approved the final version. LYM was involved in acquisition of data, analysis and interpretation of data and drafting of manuscript. CIW, TS and JH were involved in the literature review data acquisition and data interpretation. OL and HLD were involved in data collection, data analysis and critical revision of manuscript. XM was involved in data analysis and statistical support.

Statistical analysis Characteristics of nirmatrelvir/ritonavir users and non-users who had incident ALI during the observation period were compared. The association between nirmatrelvir/ritonavir use and ALI during different risk periods were estimated by comparing the rates of event occurrence. Number of incident ALI events and person-days of each risk period were calculated.