The DOI matches its Crossref record; 32 of the 32 references it cites were found in a registry or an index.
Clinical and Virological Features of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) Variants of Concern: A Retrospective Cohort Study Comparing B.1.1.7 (Alpha), B.1.351 (Beta), and B.1.617.2 (Delta)
Open accessAbstract
Background: The impact of SARS-CoV-2 variants of concern (VOCs) on disease severity is unclear. In this retrospective study, we compared the outcomes of patients infected with B.1.1.7, B.1.351, and B.1.617.2 with wild-type strains from early 2020. Methods: National surveillance data from January to May 2021 were obtained and outcomes in relation to VOCs were explored. Detailed patient-level data from all patients with VOC infection admitted to our center between December 2020 and May 2021 were analyzed. Clinical outcomes were compared with a cohort of 846 patients admitted from January to April 2020. Results: A total of 829 patients in Singapore in the study period were infected with these 3 VOCs. After adjusting for age and sex, B.1.617.2 was associated with higher odds of oxygen requirement, intensive care unit admission, or death (adjusted odds ratio [aOR], 4.90; 95% confidence interval [CI]: 1.43-30.78). Of these patients, 157 were admitted to our center. After adjusting for age, sex, comorbidities, and vaccination, the aOR for pneumonia with B.1.617.2 was 1.88 (95% CI: .95-3.76) compared with wild-type. These differences were not seen with B.1.1.7 and B.1.351. Vaccination status was associated with decreased severity. B.1.617.2 was associated with significantly lower polymerase chain reaction cycle threshold (Ct) values and longer duration of Ct value ≤30 (median duration 18 days for B.1.617.2, 13 days for wild-type). Conclusions: B.1.617.2 was associated with increased severity of illness, and with lower Ct values and longer viral shedding. These findings provide impetus for the rapid implementation of vaccination programs.
Overview
The claims and statistics of this paper haven’t been checked yet.
Run the check — free, no account needed. It reads the open-access text and checks the sources it cites.
Integrity signals
Registry
Cites
Statistics
Verification
Claims the paper makes
The claims and statistics of this paper haven’t been checked yet.
Run the check — free, no account needed. It reads the open-access text and checks the sources it cites.
Self-check
Percentages, sums and reported differences re-computed from the paper’s own numbers.
The self-check needs the paper’s full text.
Citations
Cites
SARS-CoV-2 variants, spike mutations and immune escape
Harvey, W. T., Carabelli, A. M., Jackson, B., Gupta, R. K., Thomson, E. C., Harrison, E. M., Ludden, C., Reeve, R., Rambaut, A., COVID-19 Genomics UK (COG-UK) Consortium, et al. (2021) · Nature Reviews Microbiology · doi:10.1038/s41579-021-00573-0 · Cited by 3,528
Effectiveness of Covid-19 Vaccines against the B.1.617.2 (Delta) Variant
Lopez Bernal, J., Andrews, N., Gower, C., Gallagher, E., Simmons, R., Thelwall, S., Stowe, J., Tessier, E., Groves, N., Dabrera, G., et al. (2021) · New England Journal of Medicine · doi:10.1056/nejmoa2108891 · Cited by 2,889
Estimated transmissibility and impact of SARS-CoV-2 lineage B.1.1.7 in England
Davies, N. G., Abbott, S., Barnard, R. C., Jarvis, C. I., Kucharski, A. J., Munday, J. D., Pearson, C. A. B., Russell, T. W., Tully, D. C., Washburne, A. D., et al. (2021) · Science · doi:10.1126/science.abg3055 · Cited by 2,581 · cited 1×
“While robust epidemiologic data have provided evidence for the increased transmissibility of these VOCs [4, 6, 9], their impact on clinical outcomes such as disease severity and mortality is less clear.”
Estimated transmissibility and impact of SARS-CoV-2 lineage B.1.1.7 in England
Davies, N. G., Abbott, S., Barnard, R. C., Jarvis, C. I., Kucharski, A. J., Munday, J. D., Pearson, C. A. B., Russell, T. W., Tully, D. C., Washburne, A. D., et al. (2020) · doi:10.1101/2020.12.24.20248822 · Cited by 2,557
A dynamic nomenclature proposal for SARS-CoV-2 lineages to assist genomic epidemiology
Rambaut, A., Holmes, E. C., O’Toole, Á., Hill, V., McCrone, J. T., Ruis, C., du Plessis, L., & Pybus, O. G. (2020) · Nature Microbiology · doi:10.1038/s41564-020-0770-5 · Cited by 2,543
Detection of a SARS-CoV-2 variant of concern in South Africa
Tegally, H., Wilkinson, E., Giovanetti, M., Iranzadeh, A., Fonseca, V., Giandhari, J., Doolabh, D., Pillay, S., San, E. J., Msomi, N., et al. (2021) · Nature · doi:10.1038/s41586-021-03402-9 · Cited by 2,510
Antibody resistance of SARS-CoV-2 variants B.1.351 and B.1.1.7
Wang, P., Nair, M. S., Liu, L., Iketani, S., Luo, Y., Guo, Y., Wang, M., Yu, J., Zhang, B., Kwong, P. D., et al. (2021) · Nature · doi:10.1038/s41586-021-03398-2 · Cited by 2,312
Assessing transmissibility of SARS-CoV-2 lineage B.1.1.7 in England
The COVID-19 Genomics UK (COG-UK) consortium, Volz, E., Mishra, S., Chand, M., Barrett, J. C., Johnson, R., Geidelberg, L., Hinsley, W. R., Laydon, D. J., Dabrera, G., et al. (2021) · Nature · doi:10.1038/s41586-021-03470-x · Cited by 1,611
Genomics and epidemiology of the P.1 SARS-CoV-2 lineage in Manaus, Brazil
Faria, N. R., Mellan, T. A., Whittaker, C., Claro, I. M., Candido, D. D. S., Mishra, S., Crispim, M. A. E., Sales, F. C. S., Hawryluk, I., McCrone, J. T., et al. (2021) · Science · doi:10.1126/science.abh2644 · Cited by 1,461
Lopez Bernal, J., Andrews, N., Gower, C., Robertson, C., Stowe, J., Tessier, E., Simmons, R., Cottrell, S., Roberts, R., O’Doherty, M., et al. (2021) · BMJ · doi:10.1136/bmj.n1088 · Cited by 1,389
Cited by
SARS-CoV-2 Variants of Concern
Choi, J. Y., & Smith, D. M. (2021) · Yonsei Medical Journal · doi:10.3349/ymj.2021.62.11.961 · Cited by 293
Coronavirus Disease 2019 Disease Severity in Children Infected With the Omicron Variant
Butt, A. A., Dargham, S. R., Loka, S., Shaik, R. M., Chemaitelly, H., Tang, P., Hasan, M. R., Coyle, P. V., Yassine, H. M., Al-Khatib, H. A., et al. (2022) · Clinical Infectious Diseases · doi:10.1093/cid/ciac275 · Cited by 129
Lionte, C., Sorodoc, V., Haliga, R. E., Bologa, C., Ceasovschih, A., Petris, O. R., Coman, A. E., Stoica, A., Sirbu, O., Puha, G., et al. (2022) · Diagnostics · doi:10.3390/diagnostics12061373 · Cited by 36
Metadata
- Authors
- Ong, S. W. X., Chiew, C. J., Ang, L. W., Mak, T. M., Cui, L., Toh, M. P. H. S., Lim, Y. D., Lee, P. H., Lee, T. H., Chia, P. Y., Maurer-Stroh, S., Lin, R. T. P., Leo, Y. S., Lee, V. J., Lye, D. C., & Young, B. E.
- Venue
- Clinical Infectious Diseases
- Publisher
- Oxford University Press (OUP)
- Published
- 2021-08-23
- Volume
- 75
- Issue
- 1
- Pages
- e1128-e1136
- ISSN
- 1058-4838 (ISSN-L)
- 1537-6591
- OpenAlex
- W3193641425
- Cited by
- 384
- References
- 32
- FWCI
- 26.73
- Type
- journal article
- Language
- en
- Open access
- hybrid
About these checks
Registry, retraction, Cites and statistics results are computed, not judged, with one exception: a printed reference that no index lists is read once by a model before it counts as a citation error. Claims are extracted by a model and kept only when their quote appears verbatim in the text; each cited source is then checked, with a model’s help, for whether it says what the claim relies on. Those verdicts can be wrong — read the claim’s quote and the cited source before relying on one.
Statistics and arithmetic are recomputed, not judged.
Confidence bands are shown only for fields calibrated on our annotated test set. None is calibrated yet, so no band is shown.
What counts as a claim ›How we measure confidence ›How we check this ›
Are you an author, or do you see a problem with this page? Request a review
How to cite
Cite CoChat for the checks on this page, and the paper for its own findings.
- This page
- CoChat. (2026). Citation check: Clinical and Virological Features of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) Variants of Concern: A Retrospective Cohort Study Comparing B.1.1.7 (Alpha), B.1.351 (Beta), and B.1.617.2 (Delta). https://app.cochat.ai/papers/10.1093/cid/ciab721
- The paper
- Ong, S. W. X., Chiew, C. J., Ang, L. W., Mak, T. M., Cui, L., Toh, M. P. H. S., Lim, Y. D., Lee, P. H., Lee, T. H., Chia, P. Y., Maurer-Stroh, S., Lin, R. T. P., Leo, Y. S., Lee, V. J., Lye, D. C., & Young, B. E. (2022). Clinical and Virological Features of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) Variants of Concern: A Retrospective Cohort Study Comparing B.1.1.7 (Alpha), B.1.351 (Beta), and B.1.617.2 (Delta). Clinical Infectious Diseases. https://doi.org/10.1093/cid/ciab721
Data sources
Bibliographic data: Semantic Scholar, OpenAlex, Crossref.
Contains information from the Semantic Scholar Academic Graph Datasets, made available under the ODC Attribution License (ODC-BY 1.0).
Semantic Scholar’s data is described in: Kinney, R., et al. (2023). The Semantic Scholar Open Data Platform. arXiv:2301.10140.
