Incidence, severity, risk factors and outcomes of SARS-CoV-2 reinfections during the Omicron period: a systematic review and meta-analysis
Author(s)
Type
Journal Article
Abstract
Background
Our previous systematic review estimated the cumulative incidence of SARS-CoV-2 reinfections as 1.16% (95% CI = 1.01–1.33%) during the pre-Omicron period. The Omicron variant that emerged in November 2021 was significantly genetically distinct from the previous SARS-CoV-2 variants and thus, more transmissible and posed an increased risk of SARS-CoV-2 reinfections in the population. We, therefore, conducted a fresh systematic review and meta-analysis to estimate the SARS-CoV-2 reinfection burden during the Omicron period.
Methods
We searched CINAHL, Medline, Global Health, Embase, and WHO COVID-19 in October 2023 for studies reporting the SARS-CoV-2 reinfection incidence during the Omicron period. The quality of the included studies was assessed using the Joanna Briggs Institute checklists. Random effects meta-analyses were conducted to estimate the incidence, and requirement of hospitalisation of SARS-CoV-2 reinfections. Symptomatic severity of reinfections and case fatality rates were analysed narratively.
Results
Thirty-six studies were included. The reinfection cumulative incidence during the Omicron period was 3.35% (95% CI = 1.95–5.72%) based on data from 28 studies. The cumulative incidence was higher in 18–59-year-old adults (6.62% (95% CI = 3.22–13.12%)) compared to other age groups and in health care workers (9.88% (95% CI = 5.18–18.03%)) compared to the general population (2.48% (95% CI = 1.34–4.54%)). We estimated about 1.81% (95% CI = 0.18–15.87%) of the reinfected cases required hospitalisation based on limited and highly variable data.
Conclusions
There was an increased risk of reinfections during the Omicron period compared to the pre-Omicron period. The incidence was higher in 18–59-year-old adults and health care workers and generally less severe during the Omicron period. However, data were limited on disease severity and long-term outcomes.
Our previous systematic review estimated the cumulative incidence of SARS-CoV-2 reinfections as 1.16% (95% CI = 1.01–1.33%) during the pre-Omicron period. The Omicron variant that emerged in November 2021 was significantly genetically distinct from the previous SARS-CoV-2 variants and thus, more transmissible and posed an increased risk of SARS-CoV-2 reinfections in the population. We, therefore, conducted a fresh systematic review and meta-analysis to estimate the SARS-CoV-2 reinfection burden during the Omicron period.
Methods
We searched CINAHL, Medline, Global Health, Embase, and WHO COVID-19 in October 2023 for studies reporting the SARS-CoV-2 reinfection incidence during the Omicron period. The quality of the included studies was assessed using the Joanna Briggs Institute checklists. Random effects meta-analyses were conducted to estimate the incidence, and requirement of hospitalisation of SARS-CoV-2 reinfections. Symptomatic severity of reinfections and case fatality rates were analysed narratively.
Results
Thirty-six studies were included. The reinfection cumulative incidence during the Omicron period was 3.35% (95% CI = 1.95–5.72%) based on data from 28 studies. The cumulative incidence was higher in 18–59-year-old adults (6.62% (95% CI = 3.22–13.12%)) compared to other age groups and in health care workers (9.88% (95% CI = 5.18–18.03%)) compared to the general population (2.48% (95% CI = 1.34–4.54%)). We estimated about 1.81% (95% CI = 0.18–15.87%) of the reinfected cases required hospitalisation based on limited and highly variable data.
Conclusions
There was an increased risk of reinfections during the Omicron period compared to the pre-Omicron period. The incidence was higher in 18–59-year-old adults and health care workers and generally less severe during the Omicron period. However, data were limited on disease severity and long-term outcomes.
Date Issued
2025-02-07
Date Acceptance
2025-02-01
Citation
Journal of Global Health, 2025, 15
ISSN
2047-2978
Publisher
Edinburgh University Global Health Society
Start Page
04032
Journal / Book Title
Journal of Global Health
Volume
15
Copyright Statement
© 2025 The Author(s)
License URL
Identifier
https://www.ncbi.nlm.nih.gov/pubmed/39916552
Subjects
Humans
COVID-19
Incidence
SARS-CoV-2
Risk Factors
Reinfection
Severity of Illness Index
Hospitalization
Publication Status
Published
Coverage Spatial
Scotland
Article Number
04032
Date Publish Online
2025-02-07