Post-acute sequelae of hospitalised COVID-19 re-infection compared with hospitalised first-time infection: a population-based retrospective cohort study in Hong Kong

Vincent Ka Chun Yan; Yin Zhang; Deliang Yang; Xue Li; Lung Yi Mak; Francisco T. T. Lai; Celine S. L. Chui; Eric Yuk Fai Wan; Carlos Wong; Shirley Chiu Wai Chan; Ivan F. N. Hung; Chak Sing Lau; Esther Wai Yin Chan; Ian Chi-Kei Wong

doi:10.1136/bmjph-2023-000833

Post-acute sequelae of hospitalised COVID-19 re-infection compared with hospitalised first-time infection: a population-based retrospective cohort study in Hong Kong

Vincent Ka Chun Yan
, Yin Zhang
, Deliang Yang
, Xue Li
, Lung Yi Mak
, Francisco T. T. Lai
, Celine S. L. Chui
, Eric Yuk Fai Wan
, Carlos Wong
, Shirley Chiu Wai Chan
, Ivan F. N. Hung
, Chak Sing Lau
, Esther Wai Yin Chan
, Ian Chi-Kei Wong

Laboratory of Data Discovery for Health

Research output: Contribution to journal › Article › peer-review

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Abstract

INTRODUCTION: COVID-19 infection is associated with post-acute adverse outcomes affecting multiple organ systems. Although preliminary studies have suggested that COVID-19 re-infection may have a cumulative effect on long-term outcome, differential effects of COVID-19 re-infection severe enough to be hospitalised on post-acute sequelae compared with hospitalised first-time infection have not been explored.

METHODS: Retrospective cohort study using territory-wide electronic medical records databases in Hong Kong. Adults hospitalised with COVID-19 between 1 January and 30 November 2022, who survived the first 28 days after infection and was discharged, were categorised into re-infection and first-time infection groups. Individuals with reinfection were compared with those with first-time infection for all-cause mortality, all-cause hospital readmission, attendance to the emergency department and complications during the post-acute period using propensity-score-weighted Cox regression. Subgroup analyses were conducted by age (<65 and ≥65 years), sex, Charlson Comorbidity Index (0-4, ≥5), COVID-19 vaccination (0-1, 2+doses) and hospitalisation status of previous infection.

RESULTS: 2244 patients with hospitalised COVID-19 re-infection and 58 894 patients with hospitalised first-time COVID-19 infection were included. After a median follow-up of 170 days, re-infection was associated with a significantly higher risk of post-acute all-cause mortality compared with first-time infection (adjusted HR (95% CI): 1.366 (1.166 to 1.600); incidence rate (95% CI): 7.3 (7.1 to 7.5) vs 4.6 (4.4 to 4.7) per 10 000 person-days), all-cause hospital readmission (1.297 (1.200 to 1.403); 50.5 (49.8 to 51.1) vs 28.1 (27.8 to 28.5)), and attendance to emergency departments (1.307 (1.199 to 1.425); 35.4 (34.8 to 35.9) vs 21.9 (21.6 to 22.2)). Findings were consistent across subgroups of age, sex, health status and vaccination status. A greater magnitude of increased risk was observed especially among those hospitalised during a previous infection.

CONCLUSION: Among patients with COVID-19 infection requiring hospitalisation, COVID-19 re-infection was associated with increased post-acute mortality and morbidity compared with first-time infection. Further studies are warranted to delineate the effects on complications.

Original language	English
Article number	e000833
Number of pages	13
Journal	BMJ Public Health
Volume	3
Issue number	1
Early online date	20 Jan 2025
DOIs	https://doi.org/10.1136/bmjph-2023-000833
Publication status	Published - Jan 2025

Bibliographical note

Data Access Statement

Data may be obtained from a third party and are not publicly available. Data are not available as the data custodians (the Hospital
Authority and the Department of Health of Hong Kong SAR) have not given permission for sharing due to patient confidentiality and privacy concerns. Local academic institutions, government departments or non-governmental organisations may apply for the access to data through the Hospital Authority’s data sharing portal (https://www3.ha.org.hk/data).

Funding

This work was supported by Collaborative Research Fund, University Grants Committee, the HKSAR Government (Principal Investigator: ICKW; Ref. No. C7154-20GF) and a research grant from the Food and Health Bureau; HMRF Research on COVID-19, The Government of the Hong Kong Special Administrative Region (Principal Investigator (WP2): E.W.C.; Ref: COVID1903011). ICKW and FTTL are partially supported by the Laboratory of Data Discovery for Health (D2 4H) funded by the by AIR@InnoHK administered by Innovation and Technology Commission.

UN SDGs

This output contributes to the following UN Sustainable Development Goals (SDGs)

SDG 3 Good Health and Well-being

Keywords

Epidemiology
Public Health
COVID-19

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10.1136/bmjph-2023-000833Licence: CC BY-NC 4.0

Post- acute sequelae of hospitalised COVID- 19 re-infection compared w hospitalised first-time infection_Hong Kong cohort study
Copyright © Author(s) (or their employer(s)) 2025. Re-use permitted under CC BY-NC. Published by BMJ Group.
Final published version, 298 KBLicence: CC BY-NC 4.0

Cite this

Yan, V. K. C., Zhang, Y., Yang, D., Li, X., Mak, L. Y., Lai, F. T. T., Chui, C. S. L., Wan, E. Y. F., Wong, C., Chan, S. C. W., Hung, I. F. N., Lau, C. S., Chan, E. W. Y., & Wong, I. C.-K. (2025). Post-acute sequelae of hospitalised COVID-19 re-infection compared with hospitalised first-time infection: a population-based retrospective cohort study in Hong Kong. BMJ Public Health, 3(1), Article e000833. https://doi.org/10.1136/bmjph-2023-000833

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title = "Post-acute sequelae of hospitalised COVID-19 re-infection compared with hospitalised first-time infection: a population-based retrospective cohort study in Hong Kong",

abstract = "INTRODUCTION: COVID-19 infection is associated with post-acute adverse outcomes affecting multiple organ systems. Although preliminary studies have suggested that COVID-19 re-infection may have a cumulative effect on long-term outcome, differential effects of COVID-19 re-infection severe enough to be hospitalised on post-acute sequelae compared with hospitalised first-time infection have not been explored.METHODS: Retrospective cohort study using territory-wide electronic medical records databases in Hong Kong. Adults hospitalised with COVID-19 between 1 January and 30 November 2022, who survived the first 28 days after infection and was discharged, were categorised into re-infection and first-time infection groups. Individuals with reinfection were compared with those with first-time infection for all-cause mortality, all-cause hospital readmission, attendance to the emergency department and complications during the post-acute period using propensity-score-weighted Cox regression. Subgroup analyses were conducted by age (<65 and ≥65 years), sex, Charlson Comorbidity Index (0-4, ≥5), COVID-19 vaccination (0-1, 2+doses) and hospitalisation status of previous infection.RESULTS: 2244 patients with hospitalised COVID-19 re-infection and 58 894 patients with hospitalised first-time COVID-19 infection were included. After a median follow-up of 170 days, re-infection was associated with a significantly higher risk of post-acute all-cause mortality compared with first-time infection (adjusted HR (95\% CI): 1.366 (1.166 to 1.600); incidence rate (95\% CI): 7.3 (7.1 to 7.5) vs 4.6 (4.4 to 4.7) per 10 000 person-days), all-cause hospital readmission (1.297 (1.200 to 1.403); 50.5 (49.8 to 51.1) vs 28.1 (27.8 to 28.5)), and attendance to emergency departments (1.307 (1.199 to 1.425); 35.4 (34.8 to 35.9) vs 21.9 (21.6 to 22.2)). Findings were consistent across subgroups of age, sex, health status and vaccination status. A greater magnitude of increased risk was observed especially among those hospitalised during a previous infection.CONCLUSION: Among patients with COVID-19 infection requiring hospitalisation, COVID-19 re-infection was associated with increased post-acute mortality and morbidity compared with first-time infection. Further studies are warranted to delineate the effects on complications.",

keywords = "Epidemiology, Public Health, COVID-19",

author = "Yan, \{Vincent Ka Chun\} and Yin Zhang and Deliang Yang and Xue Li and Mak, \{Lung Yi\} and Lai, \{Francisco T. T.\} and Chui, \{Celine S. L.\} and Wan, \{Eric Yuk Fai\} and Carlos Wong and Chan, \{Shirley Chiu Wai\} and Hung, \{Ivan F. N.\} and Lau, \{Chak Sing\} and Chan, \{Esther Wai Yin\} and Wong, \{Ian Chi-Kei\}",

note = "Copyright {\textcopyright} Author(s) (or their employer(s)) 2025. Re-use permitted under CC BY-NC. Published by BMJ Group.",

year = "2025",

month = jan,

doi = "10.1136/bmjph-2023-000833",

language = "English",

volume = "3",

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Yan, VKC, Zhang, Y, Yang, D, Li, X, Mak, LY, Lai, FTT, Chui, CSL, Wan, EYF, Wong, C, Chan, SCW, Hung, IFN, Lau, CS, Chan, EWY & Wong, IC-K 2025, 'Post-acute sequelae of hospitalised COVID-19 re-infection compared with hospitalised first-time infection: a population-based retrospective cohort study in Hong Kong', BMJ Public Health, vol. 3, no. 1, e000833. https://doi.org/10.1136/bmjph-2023-000833

TY - JOUR

T1 - Post-acute sequelae of hospitalised COVID-19 re-infection compared with hospitalised first-time infection: a population-based retrospective cohort study in Hong Kong

AU - Yan, Vincent Ka Chun

AU - Zhang, Yin

AU - Yang, Deliang

AU - Li, Xue

AU - Mak, Lung Yi

AU - Lai, Francisco T. T.

AU - Chui, Celine S. L.

AU - Wan, Eric Yuk Fai

AU - Wong, Carlos

AU - Chan, Shirley Chiu Wai

AU - Hung, Ivan F. N.

AU - Lau, Chak Sing

AU - Chan, Esther Wai Yin

AU - Wong, Ian Chi-Kei

PY - 2025/1

Y1 - 2025/1

N2 - INTRODUCTION: COVID-19 infection is associated with post-acute adverse outcomes affecting multiple organ systems. Although preliminary studies have suggested that COVID-19 re-infection may have a cumulative effect on long-term outcome, differential effects of COVID-19 re-infection severe enough to be hospitalised on post-acute sequelae compared with hospitalised first-time infection have not been explored.METHODS: Retrospective cohort study using territory-wide electronic medical records databases in Hong Kong. Adults hospitalised with COVID-19 between 1 January and 30 November 2022, who survived the first 28 days after infection and was discharged, were categorised into re-infection and first-time infection groups. Individuals with reinfection were compared with those with first-time infection for all-cause mortality, all-cause hospital readmission, attendance to the emergency department and complications during the post-acute period using propensity-score-weighted Cox regression. Subgroup analyses were conducted by age (<65 and ≥65 years), sex, Charlson Comorbidity Index (0-4, ≥5), COVID-19 vaccination (0-1, 2+doses) and hospitalisation status of previous infection.RESULTS: 2244 patients with hospitalised COVID-19 re-infection and 58 894 patients with hospitalised first-time COVID-19 infection were included. After a median follow-up of 170 days, re-infection was associated with a significantly higher risk of post-acute all-cause mortality compared with first-time infection (adjusted HR (95% CI): 1.366 (1.166 to 1.600); incidence rate (95% CI): 7.3 (7.1 to 7.5) vs 4.6 (4.4 to 4.7) per 10 000 person-days), all-cause hospital readmission (1.297 (1.200 to 1.403); 50.5 (49.8 to 51.1) vs 28.1 (27.8 to 28.5)), and attendance to emergency departments (1.307 (1.199 to 1.425); 35.4 (34.8 to 35.9) vs 21.9 (21.6 to 22.2)). Findings were consistent across subgroups of age, sex, health status and vaccination status. A greater magnitude of increased risk was observed especially among those hospitalised during a previous infection.CONCLUSION: Among patients with COVID-19 infection requiring hospitalisation, COVID-19 re-infection was associated with increased post-acute mortality and morbidity compared with first-time infection. Further studies are warranted to delineate the effects on complications.

AB - INTRODUCTION: COVID-19 infection is associated with post-acute adverse outcomes affecting multiple organ systems. Although preliminary studies have suggested that COVID-19 re-infection may have a cumulative effect on long-term outcome, differential effects of COVID-19 re-infection severe enough to be hospitalised on post-acute sequelae compared with hospitalised first-time infection have not been explored.METHODS: Retrospective cohort study using territory-wide electronic medical records databases in Hong Kong. Adults hospitalised with COVID-19 between 1 January and 30 November 2022, who survived the first 28 days after infection and was discharged, were categorised into re-infection and first-time infection groups. Individuals with reinfection were compared with those with first-time infection for all-cause mortality, all-cause hospital readmission, attendance to the emergency department and complications during the post-acute period using propensity-score-weighted Cox regression. Subgroup analyses were conducted by age (<65 and ≥65 years), sex, Charlson Comorbidity Index (0-4, ≥5), COVID-19 vaccination (0-1, 2+doses) and hospitalisation status of previous infection.RESULTS: 2244 patients with hospitalised COVID-19 re-infection and 58 894 patients with hospitalised first-time COVID-19 infection were included. After a median follow-up of 170 days, re-infection was associated with a significantly higher risk of post-acute all-cause mortality compared with first-time infection (adjusted HR (95% CI): 1.366 (1.166 to 1.600); incidence rate (95% CI): 7.3 (7.1 to 7.5) vs 4.6 (4.4 to 4.7) per 10 000 person-days), all-cause hospital readmission (1.297 (1.200 to 1.403); 50.5 (49.8 to 51.1) vs 28.1 (27.8 to 28.5)), and attendance to emergency departments (1.307 (1.199 to 1.425); 35.4 (34.8 to 35.9) vs 21.9 (21.6 to 22.2)). Findings were consistent across subgroups of age, sex, health status and vaccination status. A greater magnitude of increased risk was observed especially among those hospitalised during a previous infection.CONCLUSION: Among patients with COVID-19 infection requiring hospitalisation, COVID-19 re-infection was associated with increased post-acute mortality and morbidity compared with first-time infection. Further studies are warranted to delineate the effects on complications.

KW - Epidemiology

KW - Public Health

KW - COVID-19

UR - https://bmjpublichealth.bmj.com/content/3/1/e000833

U2 - 10.1136/bmjph-2023-000833

DO - 10.1136/bmjph-2023-000833

M3 - Article

C2 - 40017919

SN - 2753-4294

VL - 3

JO - BMJ Public Health

JF - BMJ Public Health

IS - 1

M1 - e000833

ER -

Post-acute sequelae of hospitalised COVID-19 re-infection compared with hospitalised first-time infection: a population-based retrospective cohort study in Hong Kong

Abstract

Bibliographical note

Data Access Statement

Funding

UN SDGs

Keywords

Access to Document

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