The DOI matches its Crossref record; 73 of the 79 references it cites were found in a registry or an index.
What defines an efficacious COVID-19 vaccine? A review of the challenges assessing the clinical efficacy of vaccines against SARS-CoV-2
Open accessAbstract
The novel coronavirus, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has caused more than 1 million deaths in the first 6 months of the pandemic and huge economic and social upheaval internationally. An efficacious vaccine is essential to prevent further morbidity and mortality. Although some countries might deploy COVID-19 vaccines on the strength of safety and immunogenicity data alone, the goal of vaccine development is to gain direct evidence of vaccine efficacy in protecting humans against SARS-CoV-2 infection and COVID-19 so that manufacture of efficacious vaccines can be selectively upscaled. A candidate vaccine against SARS-CoV-2 might act against infection, disease, or transmission, and a vaccine capable of reducing any of these elements could contribute to disease control. However, the most important efficacy endpoint, protection against severe disease and death, is difficult to assess in phase 3 clinical trials. In this Review, we explore the challenges in assessing the efficacy of candidate SARS-CoV-2 vaccines, discuss the caveats needed to interpret reported efficacy endpoints, and provide insight into answering the seemingly simple question, "Does this COVID-19 vaccine work?"
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.
Claims other papers make about this one
Each is checked against this paper’s own text: does it say what the citing paper says it does?
The cited source says what the claim attributes to it.
In the citing paper
“the long-term risks and benefits of a SARS-CoV-2 vaccine will take a long time to fully evaluate in adults33 while the public health needs of a vaccine are pressing.”
From SARS-CoV-2 vaccine testing and trials in the pediatric population: biologic, ethical, research, and implementation challenges (2021) · cites this paper as [33]
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
An interactive web-based dashboard to track COVID-19 in real time
Dong, E., Du, H., & Gardner, L. (2020) · The Lancet Infectious Diseases · doi:10.1016/s1473-3099(20)30120-1 · Cited by 10,048
Virological assessment of hospitalized patients with COVID-2019
Wölfel, R., Corman, V. M., Guggemos, W., Seilmaier, M., Zange, S., Müller, M. A., Niemeyer, D., Jones, T. C., Vollmar, P., Rothe, C., et al. (2020) · Nature · doi:10.1038/s41586-020-2196-x · Cited by 6,661
Temporal dynamics in viral shedding and transmissibility of COVID-19
He, X., Lau, E. H. Y., Wu, P., Deng, X., Wang, J., Hao, X., Lau, Y. C., Wong, J. Y., Guan, Y., Tan, X., et al. (2020) · Nature Medicine · doi:10.1038/s41591-020-0869-5 · Cited by 4,300
Estimates of the severity of coronavirus disease 2019: a model-based analysis
Verity, R., Okell, L. C., Dorigatti, I., Winskill, P., Whittaker, C., Imai, N., Cuomo-Dannenburg, G., Thompson, H., Walker, P. G. T., Fu, H., et al. (2020) · The Lancet Infectious Diseases · doi:10.1016/s1473-3099(20)30243-7 · Cited by 3,660
Docherty, A. B., Harrison, E. M., Green, C. A., Hardwick, H. E., Pius, R., Norman, L., Holden, K. A., Read, J. M., Dondelinger, F., Carson, G., et al. (2020) · BMJ · doi:10.1136/bmj.m1985 · Cited by 3,481
To, K. K., Tsang, O. T.-Y., Leung, W.-S., Tam, A. R., Wu, T.-C., Lung, D. C., Yip, C. C., Cai, J., Chan, J. M., Chik, T. S., et al. (2020) · The Lancet Infectious Diseases · doi:10.1016/s1473-3099(20)30196-1 · Cited by 3,045
Antibody responses to SARS-CoV-2 in patients with COVID-19
Long, Q.-X., Liu, B.-Z., Deng, H.-J., Wu, G.-C., Deng, K., Chen, Y.-K., Liao, P., Qiu, J.-F., Lin, Y., Cai, X.-F., et al. (2020) · Nature Medicine · doi:10.1038/s41591-020-0897-1 · Cited by 2,876
Antibody Responses to SARS-CoV-2 in Patients With Novel Coronavirus Disease 2019
Zhao, J., Yuan, Q., Wang, H., Liu, W., Liao, X., Su, Y., Wang, X., Yuan, J., Li, T., Li, J., et al. (2020) · Clinical Infectious Diseases · doi:10.1093/cid/ciaa344 · Cited by 2,607
Prevalence of Asymptomatic SARS-CoV-2 Infection
Oran, D. P., & Topol, E. J. (2020) · Annals of Internal Medicine · doi:10.7326/m20-3012 · Cited by 2,348
The Architecture of SARS-CoV-2 Transcriptome
Kim, D., Lee, J.-Y., Yang, J.-S., Kim, J. W., Kim, V. N., & Chang, H. (2020) · Cell · doi:10.1016/j.cell.2020.04.011 · Cited by 2,123
Research works printed but not linked: 1
- Yu, 2020, DNA vaccine protection against SARS-CoV-2 in rhesus macaques, Science, 369, 806, 10.1126/science.abc6284 · DOI · Paper page
Cited by
Sorted by citations
Items 601–633 of 633
MONITORING THE CURRENT STATE OF VACCINATION (REVIEW)
Ogly, T. S. S., Zakirjanovna, D. M., & Gumarovna, A. K. (2024) · International Journal of Advance Scientific Research · doi:10.37547/ijasr-04-03-17
Prasetyo, M. E., Soegiarto, G., & Wulandari, L. (2023) · Bali Medical Journal · doi:10.15562/bmj.v13i1.4710
PREDICTIVE FACTORS FOR MORTALITY FROM DELTA VARIANT OF SARS-COV-2 IN REPUBLIC OF NORTH MACEDONIA
Kochinski, D., Stefanovska, V. V., Kljuseva, S. P., & Memeti, S. (2024) · Journal of Morphological Sciences · doi:10.55302/jms2471040k
Kochinski, D., Stefanovska, V. V., Kljuseva, S. P., Pollozhani, E., & Memeti, S. (2024) · Journal of Morphological Sciences · doi:10.55302/jms2471033k
1COVID-19 Mortality in Kerbala-Iraq
(2024) · Journal of Clinical & Experimental Immunology · doi:10.33140/jcei.09.01.02
Moreira, A. G., & Arditi, M. (2024) · Elsevier eBooks · doi:10.1016/b978-0-323-79525-8.00040-8
Faustini, J. B., Campanelli, A. P., Fraga‐Silva, T. F. D. C., & de Souza, V. N. B. (2024) · REVISTA DO INSTITUTO ADOLFO LUTZ · doi:10.53393/rial.2024.v.83.40020
Forslid, R., & Herzing, M. (2024) · International Journal of Health Economics and Management · doi:10.1007/s10754-024-09384-1
Navigating Immune Landscapes: Insights From A Prospective Study
Badaruddin, I. A., Othman, H., Shuaib, W. M. A. W., Yusof, M. Z. C., Othman, S., Ali, M. N. A., Mat, I. M., Mansor, M. M., & Nawi, A. M. (2024) · Asia Pacific Journal of Public Health · doi:10.1177/10105395241282621
Patel, T., Patel, D. P., El-Sayed, H., Sanyal, M., & Shrivastav, P. S. (2024) · bioRxiv (Cold Spring Harbor Laboratory) · doi:10.1101/2024.10.11.617884
Owlia, F., Kargar, M.-J., & Kazemipoor, M. (2025) · Egyptian Journal of Bronchology · doi:10.1186/s43168-025-00362-w
ISOLAMENTO, SAÚDE MENTAL, COMPOSIÇÃO CORPORAL DE DOCENTES DE EDUCAÇÃO FÍSICA
Leite, T. S. C., MELO, F. A. D. A., Júnior, A. L. D. C., & Neto, G. R. (2025) · Fiep Bulletin - online · doi:10.16887/cmabfk78
Epidemiological-Based Study of SARS-CoV-2 in Faisalabad
Ullah, S., Khan, M. W., Qurat-ul-Ain, Q.-U.-A., Farva, K., Khan, N. M., & Ullah, H. (2025) · Zoonotic Diseases · doi:10.3390/zoonoticdis5030023
Williams, L. R., Voysey, M., Pollard, A. J., & Grassly, N. C. (2025) · Vaccine · doi:10.1016/j.vaccine.2025.127856
Self-citationKose, P., BAYINDIRLI, K., Arslan, A. O., & Anakök, Ö. F. (2025) · International Journal of Peptide Research and Therapeutics · doi:10.1007/s10989-025-10775-2
Thakataka, A. S., Mberikunashe, J., Govha, E., Juru, T., Gombe, N. T., & Tshimanga, M. (2024) · Journal of Interventional Epidemiology and Public Health · doi:10.37432/jieph.2024.7.2.108
Coşan, F., Demirel, O. U., Yalcin, D., SONKAYA, M. M., ULUIŞIK, I. E., Cecen, O., Furuncuoğlu, Y., Celikmen, D. M., Kara, O., Ceylan, E., et al. (2024) · Figshare · doi:10.6084/m9.figshare.26605021
Coşan, F., Demirel, O. U., Yalcin, D., SONKAYA, M. M., ULUIŞIK, I. E., Cecen, O., Furuncuoğlu, Y., Celikmen, D. M., Kara, O., Ceylan, E., et al. (2024) · Figshare · doi:10.6084/m9.figshare.26605018
Wang, S., Peng, H., Chen, F., Liu, C., Zheng, Q., Wang, M., Wang, J., Yu, H., Xue, E., Chen, X., et al. (2024) · Figshare · doi:10.6084/m9.figshare.26639962
Coşan, F., Demirel, O. U., Yalcin, D., SONKAYA, M. M., ULUIŞIK, I. E., Cecen, O., Furuncuoğlu, Y., Celikmen, D. M., Kara, O., Ceylan, E., et al. (2024) · Figshare · doi:10.6084/m9.figshare.26605015
Jani, B. R., Bhalani, U., Parekh, K., Vaghela, U. P., Keetha, N. R., & Balaramegowda, D. H. (2026) · Advances in computational intelligence and robotics book series · doi:10.4018/979-8-3373-6400-1.ch004
Amoako, N., Cohuet, S., Adjei, M. R., Gurry, C., Oduro, A. R., Agyapong, P. D., Musah, O., Asante, I. A., Awuah, A. A.-A., Ayivor-Djanie, R., et al. (2026) · Vaccine · doi:10.1016/j.vaccine.2026.128310
Borges, M. C., Palácios, R., Conde, M. T. R. P., Volpe, G. J., Ferreira, N. N., Garibaldi, P. M. M., da Fonseca, B. A. L., Calado, R. T., Coutinho, B. M., Gomes, B. B. M., et al. (2026) · Scientific Reports · doi:10.1038/s41598-026-37815-1
Rooyakkers, A., Ye, L., Cahn, P. E., Ruiz-Palacios, G. M., Ikram, A., Lanas, F. T., Navarro, S. R. M., Sued, O. G., Анатольевич, Л. Д., Dzutseva, V., et al. (2026) · Vaccine · doi:10.1016/j.vaccine.2026.128424
Évaluer la balance bénéfices-risques des médicaments
Cracowski, J., Molimard, M., Richard, V. J., Roustit, M., & Khouri, C. (2026) · médecine/sciences · doi:10.1051/medsci/2026040
Walmsley, S. L., Nabipoor, M., Qi, F., Lovblom, L. E., Ravindran, R., Colwill, K., & Gingras, A. (2026) · Clinical & Translational Immunology · doi:10.1002/cti2.70095 · Cited by 1
Ismaili, A. A., & Maghfiroh, M. F. N. (2026) · Transportation research procedia · doi:10.1016/j.trpro.2026.03.029
Manickum, V. K., & Mathibe, L. J. (2026) · Health SA Gesondheid · doi:10.4102/hsag.v31i0.3331
Miléo, F. C., López, L. Z., Ferreira, M. D., dos Santos, F. A., & Bortoluzzi, M. C. (2026) · Brazilian Archives of Biology and Technology · doi:10.1590/1678-4324-2026250172
Rethinking placebo control in infant vaccine trials: A mechanistic and methodological perspective
Zhang, Y. (2026) · Journal of Biomed Research · doi:10.46439/biomedres.7.088
Rai, P., & Bera, S. (2026) · Journal of Humanitarian Logistics and Supply Chain Management · doi:10.1108/jhlscm-11-2025-0251
Metadata
- Authors
- Hodgson, S. H., Mansatta, K., Mallett, G., Harris, V., Emary, K. R. W., & Pollard, A. J.
- Affiliations
- University of Oxford (GB)
- Corresponding author
- Hodgson, Susanne H
- ORCID
- Venue
- The Lancet Infectious Diseases
- Publisher
- Elsevier BV
- Published
- 2021-02
- Volume
- 21
- Issue
- 2
- Pages
- e26-e35
- ISSN
- 1473-3099 (ISSN-L)
- PMC
- PMC7837315
- OpenAlex
- W3088489318
- Cited by
- 633
- References
- 79
- Citations by year
- 2026: 11 · 2025: 14 · 2024: 52 · 2023: 99 · 2022: 221 · 2021: 221
- FWCI
- 6.56
- Type
- journal article
- Language
- en
- Open access
- bronze
- doi.org
- Locations
- The Lancet Infectious Diseases (publishedVersion)
- PubMed Central (publishedVersion)
- PubMed (publishedVersion)
- Funders
- UK Research and Innovation (MC_PC_19055)
- Coalition for Epidemic Preparedness Innovations
- National Institute for Health Research
- Topics
- Health Sciences › Medicine › Infectious Diseases › SARS-CoV-2 and COVID-19 Research
- Health Sciences › Medicine › Infectious Diseases › COVID-19 Clinical Research Studies
- Physical Sciences › Mathematics › Modeling and Simulation › COVID-19 epidemiological studies
- Keywords
- COVID-19 vaccines, SARS-CoV-2, vaccine efficacy, efficacy endpoints, vaccine development
- MeSH terms
- Immunogenicity, Vaccine, COVID-19, SARS-CoV-2, COVID-19 Vaccines, Clinical Trials as Topic, Humans, Research Design, Vaccination, Treatment Outcome, Outcome Assessment, Health Care
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