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Wang B, Andraweera P, Elliott S, Mohammed H, Lassi Z, Twigger A, Borgas C, Gunasekera S, Ladhani S, Marshall HS. Asymptomatic SARS-CoV-2 Infection by Age: A Global Systematic Review and Meta-analysis. Pediatr Infect Dis J 2023; 42:232-239. [PMID: 36730054 PMCID: PMC9935239 DOI: 10.1097/inf.0000000000003791] [Citation(s) in RCA: 21] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 11/05/2022] [Indexed: 02/03/2023]
Abstract
BACKGROUND Asymptomatic SARS-CoV-2 infections have raised concerns for public health policies to manage epidemics. This systematic review and meta-analysis aimed to estimate the age-specific proportion of asymptomatic SARS-CoV-2 infected persons globally by year of age. METHODS We searched PubMed, Embase, medRxiv and Google Scholar on September 10, 2020, and March 1, 2021. We included studies conducted during January to December 2020, before routine vaccination against COVID-19. Because we expected the relationship between the asymptomatic proportion and age to be nonlinear, multilevel mixed-effects logistic regression (QR decomposition) with a restricted cubic spline was used to model asymptomatic proportions as a function of age. RESULTS A total of 38 studies were included in the meta-analysis. In total, 6556 of 14,850 cases were reported as asymptomatic. The overall estimate of the proportion of people who became infected with SARS-CoV-2 and remained asymptomatic throughout infection was 44.1% (6556/14,850, 95% CI: 43.3%-45.0%). The predicted asymptomatic proportion peaked in children (36.2%, 95% CI: 26.0%-46.5%) at 13.5 years, gradually decreased by age and was lowest at 90.5 years of age (8.1%, 95% CI: 3.4%-12.7%). CONCLUSIONS Given the high rates of asymptomatic carriage in adolescents and young adults and their active role in virus transmission in the community, heightened vigilance and public health strategies are needed among these individuals to prevent disease transmission.
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Affiliation(s)
- Bing Wang
- From the Vaccinology and Immunology Research Trials Unit, Women’s and Children’s Health Network, Adelaide, South Australia, Australia
- Robinson Research Institute and Adelaide Medical School, The University of Adelaide, Adelaide, South Australia, Australia
| | - Prabha Andraweera
- From the Vaccinology and Immunology Research Trials Unit, Women’s and Children’s Health Network, Adelaide, South Australia, Australia
- Robinson Research Institute and Adelaide Medical School, The University of Adelaide, Adelaide, South Australia, Australia
| | - Salenna Elliott
- From the Vaccinology and Immunology Research Trials Unit, Women’s and Children’s Health Network, Adelaide, South Australia, Australia
- Robinson Research Institute and Adelaide Medical School, The University of Adelaide, Adelaide, South Australia, Australia
| | - Hassen Mohammed
- From the Vaccinology and Immunology Research Trials Unit, Women’s and Children’s Health Network, Adelaide, South Australia, Australia
- Robinson Research Institute and Adelaide Medical School, The University of Adelaide, Adelaide, South Australia, Australia
| | - Zohra Lassi
- From the Vaccinology and Immunology Research Trials Unit, Women’s and Children’s Health Network, Adelaide, South Australia, Australia
- Robinson Research Institute and Adelaide Medical School, The University of Adelaide, Adelaide, South Australia, Australia
| | | | | | | | - Shamez Ladhani
- Immunisation Division, UK Health Security Agency, London, UK; Paediatric Infectious Diseases Research Group, St George’s University of London, London, United Kingdom
| | - Helen Siobhan Marshall
- From the Vaccinology and Immunology Research Trials Unit, Women’s and Children’s Health Network, Adelaide, South Australia, Australia
- Robinson Research Institute and Adelaide Medical School, The University of Adelaide, Adelaide, South Australia, Australia
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Sah P, Fitzpatrick MC, Zimmer CF, Abdollahi E, Juden-Kelly L, Moghadas SM, Singer BH, Galvani AP. Asymptomatic SARS-CoV-2 infection: A systematic review and meta-analysis. Proc Natl Acad Sci U S A 2021; 118:e2109229118. [PMID: 34376550 PMCID: PMC8403749 DOI: 10.1073/pnas.2109229118] [Citation(s) in RCA: 265] [Impact Index Per Article: 88.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Quantification of asymptomatic infections is fundamental for effective public health responses to the COVID-19 pandemic. Discrepancies regarding the extent of asymptomaticity have arisen from inconsistent terminology as well as conflation of index and secondary cases which biases toward lower asymptomaticity. We searched PubMed, Embase, Web of Science, and World Health Organization Global Research Database on COVID-19 between January 1, 2020 and April 2, 2021 to identify studies that reported silent infections at the time of testing, whether presymptomatic or asymptomatic. Index cases were removed to minimize representational bias that would result in overestimation of symptomaticity. By analyzing over 350 studies, we estimate that the percentage of infections that never developed clinical symptoms, and thus were truly asymptomatic, was 35.1% (95% CI: 30.7 to 39.9%). At the time of testing, 42.8% (95% prediction interval: 5.2 to 91.1%) of cases exhibited no symptoms, a group comprising both asymptomatic and presymptomatic infections. Asymptomaticity was significantly lower among the elderly, at 19.7% (95% CI: 12.7 to 29.4%) compared with children at 46.7% (95% CI: 32.0 to 62.0%). We also found that cases with comorbidities had significantly lower asymptomaticity compared to cases with no underlying medical conditions. Without proactive policies to detect asymptomatic infections, such as rapid contact tracing, prolonged efforts for pandemic control may be needed even in the presence of vaccination.
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Affiliation(s)
- Pratha Sah
- Center for Infectious Disease Modeling and Analysis, Yale School of Public Health, New Haven, CT 06520
| | - Meagan C Fitzpatrick
- Center for Infectious Disease Modeling and Analysis, Yale School of Public Health, New Haven, CT 06520
- Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, MD 21201
| | - Charlotte F Zimmer
- Center for Infectious Disease Modeling and Analysis, Yale School of Public Health, New Haven, CT 06520
| | - Elaheh Abdollahi
- Agent-Based Modelling Laboratory, York University, Toronto, ON M3J 1P3, Canada
| | - Lyndon Juden-Kelly
- Agent-Based Modelling Laboratory, York University, Toronto, ON M3J 1P3, Canada
| | - Seyed M Moghadas
- Agent-Based Modelling Laboratory, York University, Toronto, ON M3J 1P3, Canada
| | - Burton H Singer
- Emerging Pathogens Institute, University of Florida, Gainesville, FL 32610
| | - Alison P Galvani
- Center for Infectious Disease Modeling and Analysis, Yale School of Public Health, New Haven, CT 06520
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