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JMIR Public Health Surveill
. 2026 Feb 9:12:e75635.
doi: 10.2196/75635.
Postpandemic Change in Demographic and Clinical Features of Patients With Omicron Who Were Hospitalized: Territory-Wide Retrospective Repeated Cross-Sectional Study in Hong Kong
Christie J Y Ching 1 , Sunny C L Chan 1 , Teddy T L Lee 1 , Hugo H H Pui 1 , Bosco K H Leung 1 , Man Sing Wong 2 , Tafu Yamamoto 3 , Chak Kwan Tong 4 , Cantian Wang 5 , Timothy H Rainer 1 , Abraham K C Wai 1 5 6
Affiliations
Background: The Omicron variant of SARS-CoV-2 underwent several mutations since it was first identified in November 2021, with a large outbreak in Hong Kong in early 2022. Yet, local cases of Omicron infections persist, even though the COVID-19 pandemic ended in May 2023.
Objective: This study aims to describe the changes in demographic and clinical characteristics of patients infected with COVID-19 across different Omicron waves in Hong Kong and determine whether the changes continued into the postpandemic period.
Methods: This retrospective repeated cross-sectional study collected data on patients infected with COVID-19 admitted to public hospitals in Hong Kong between May 1, 2022, and May 31, 2024. These data were later categorized into 3 periods based on the Omicron strain. A subsequent age-stratified descriptive analysis was conducted on each characteristic to identify any significant differences across the periods.
Results: First, the case fatality ratio significantly lowered among those older than 85 years (1.5% proportion decrease, period 1: 11.6%, period 2: 10.1%, effect size: 0.02; P<.001). Second, most patients were Chinese (≥68.7% per age group and period), and females were predominantly infected for those aged older than 85 years (≥56.9% per period). Third, the Charlson Comorbidity Index scores in most age groups showed a predominant proportion of infected individuals with 0 scores (more than 70% per period). Fourth, most cases were from slightly disadvantaged populations in Hong Kong (≥30.5% per age group per period). Fifth, clinical management of Omicron hospitalizations showed lowered length of hospital stays among adults and older individuals (≥1 d decrease between periods 1 and 3, per age group), as well as increased administration of bronchodilators.
Conclusions: Despite the decreasing incidence of Omicron cases admitted to public hospitals in Hong Kong, the increasing case fatality ratio with age suggests that long-term surveillance of COVID-19 should be maintained to prepare for potential mutations and outbreaks.
Keywords: COVID-19; Omicron; SARS-CoV-2; emergency department; infectious disease epidemiology.
. 2026 Feb 9:12:e75635.
doi: 10.2196/75635.
Postpandemic Change in Demographic and Clinical Features of Patients With Omicron Who Were Hospitalized: Territory-Wide Retrospective Repeated Cross-Sectional Study in Hong Kong
Christie J Y Ching 1 , Sunny C L Chan 1 , Teddy T L Lee 1 , Hugo H H Pui 1 , Bosco K H Leung 1 , Man Sing Wong 2 , Tafu Yamamoto 3 , Chak Kwan Tong 4 , Cantian Wang 5 , Timothy H Rainer 1 , Abraham K C Wai 1 5 6
Affiliations
- PMID: 41662574
- DOI: 10.2196/75635
Background: The Omicron variant of SARS-CoV-2 underwent several mutations since it was first identified in November 2021, with a large outbreak in Hong Kong in early 2022. Yet, local cases of Omicron infections persist, even though the COVID-19 pandemic ended in May 2023.
Objective: This study aims to describe the changes in demographic and clinical characteristics of patients infected with COVID-19 across different Omicron waves in Hong Kong and determine whether the changes continued into the postpandemic period.
Methods: This retrospective repeated cross-sectional study collected data on patients infected with COVID-19 admitted to public hospitals in Hong Kong between May 1, 2022, and May 31, 2024. These data were later categorized into 3 periods based on the Omicron strain. A subsequent age-stratified descriptive analysis was conducted on each characteristic to identify any significant differences across the periods.
Results: First, the case fatality ratio significantly lowered among those older than 85 years (1.5% proportion decrease, period 1: 11.6%, period 2: 10.1%, effect size: 0.02; P<.001). Second, most patients were Chinese (≥68.7% per age group and period), and females were predominantly infected for those aged older than 85 years (≥56.9% per period). Third, the Charlson Comorbidity Index scores in most age groups showed a predominant proportion of infected individuals with 0 scores (more than 70% per period). Fourth, most cases were from slightly disadvantaged populations in Hong Kong (≥30.5% per age group per period). Fifth, clinical management of Omicron hospitalizations showed lowered length of hospital stays among adults and older individuals (≥1 d decrease between periods 1 and 3, per age group), as well as increased administration of bronchodilators.
Conclusions: Despite the decreasing incidence of Omicron cases admitted to public hospitals in Hong Kong, the increasing case fatality ratio with age suggests that long-term surveillance of COVID-19 should be maintained to prepare for potential mutations and outbreaks.
Keywords: COVID-19; Omicron; SARS-CoV-2; emergency department; infectious disease epidemiology.