Safety and efficacy of malaria vaccine candidate R21/Matrix-M in African children: a multicentre, double-blind, randomised, phase 3 trial.
Datoo MS, Dicko A, Tinto H, Ouédraogo JB, Hamaluba M, Olotu A, Beaumont E, Ramos Lopez F, Natama HM, Weston S, Chemba M, Compaore YD, Issiaka D, Salou D, Some AM, Omenda S, Lawrie A, Bejon P, Rao H, Chandramohan D, Roberts R, Bharati S, Stockdale L, Gairola S, Greenwood BM, Ewer KJ, Bradley J, Kulkarni PS, Shaligram U, Hill AVS, R21/Matrix-M Phase 3 Trial Group
- DOI
- 10.1016/S0140-6736(23)02511-4
- Record issued
- 2026-08-10
- Engine
- 7.29.0
- Exported
- 2026-09-21
Prepared by Alpha1. This document is confidential: it is intended for the recipient it was shared with and must not be redistributed. The live record at alpha1science.com/verify/f3b58094-cb2f-4555-b9a0-1a35b31074ee is authoritative.
How this rating was calculated
- ReportingEthical approvals partially met−0.25★
- ReportingStatistical analysis partially met−0.25★
- CitationsUnresolved reference−0.25★
- The numeric-impossibility checks (GRIM/GRIMMER/DEBIT/SPRITE) did not run on this paper: the pass that reads its reported means did not complete. No reported mean was checked for arithmetic impossibility.
This Kaimen Rigor review uses Kaimen Rigor reviewers trained on a curated corpus of high-fidelity and retracted papers, with expert supervision and curation. It can still make mistakes; verify each finding against the source before relying on it.
The paper reports a well-designed phase 3 trial of the R21/Matrix-M malaria vaccine with rigorous randomisation, blinding, and pre-specified analysis. Minor reporting gaps include missing explicit regulatory compliance statement, threshold p-values, and some internal consistency issues in the text and tables.
This evaluation integrates two independent rigor reviews and a copyedit pass. Both reviewers agreed on most dimensions; the only disagreement was on statistical analysis (pass vs. warn), which we resolved to warn due to threshold p-values. The citation verification component found one preprint reference not located in a registry. All five recomputed statistics were consistent.
Numerical inconsistencies
None foundValues that contradict each other or are impossible for the stated sample: recomputed p-values and test statistics, GRIM/GRIMMER checks on summary numbers, percentages against their own counts, totals against their parts, and estimates against their own confidence intervals.
Checked — nothing surfaced.
Recomputed 5 tests: 5 consistent, 0 inconsistent; 5 via agent-written checks.
- CONSISTENTreported p < .001 · recomputed p = <.001Reviewer 1Two-tailed p-value for seasonal site vaccine efficacy against first clinical malaria episode (HR=0.25, 95% CI 0.21-0.29)
“vaccine efficacy was 75% (95% CI 71–79; p<0·0001) at the seasonal sites”
Taken as given: The 95% CI is for the efficacy (1-HR), so the CI for HR is (0.21, 0.29); The p-value is from a Cox regression test of HR=1; The function pCI works on the log scale for a ratioMethod: Computed p from the hazard ratio and its 95% confidence interval using the normal approximation on the log scale.How we recomputed it: pCI(0.25, 0.21, 0.29, 1) - CONSISTENTreported p < .001 · recomputed p = <.001Reviewer 1Two-tailed p-value for standard site vaccine efficacy (HR=0.32, 95% CI 0.26-0.39)
“vaccine efficacy was 68% (61–74; p<0·0001) at the standard sites”
Taken as given: The 95% CI is for the efficacy, so the CI for HR is (0.26, 0.39); The p-value is from a Cox regression test of HR=1Method: Computed p from the hazard ratio and its 95% confidence interval using the normal approximation on the log scale.How we recomputed it: pCI(0.32, 0.26, 0.39, 1) - CONSISTENTreported p < .001 · recomputed p = <.001Reviewer 1Two-tailed p-value for seasonal site vaccine efficacy in 5-17 month age group (HR=0.21, 95% CI 0.16-0.27)
“vaccine efficacy in children aged 5–17 months was 79% (95% CI 73–84) and, at standard sites, this efficacy was 75% (65–83).”
Taken as given: The 95% CI is for the efficacy, so HR CI is (0.16, 0.27); The p-value is from a Cox regression test of HR=1; The reported p-value is <0.001Method: Computed p from the hazard ratio and its 95% confidence interval using the normal approximation on the log scale.How we recomputed it: pCI(0.21, 0.16, 0.27, 1) - CONSISTENTreported p < .001 · recomputed p = <.001Reviewer 2Recompute two-sided Pearson chi-square p for 12-month asymptomatic parasitaemia comparison (control 73/1436 vs R21 73/2917) and compare with reported p<0.0001.
“Cross-sectional blood films at 12 months after the primary series showed asymptomatic parasitaemia that was significantly higher in the control group, with 73 (5·1%) of 1436 participants having parasitaemia without fever, compared with 73 (2·5%) of 2917 participants in the R21/Matrix-M group (p<0·0001).”
Taken as given: The 73 and 1436 are the event count and group total for the control arm; The 73 and 2917 are the event count and group total for the R21/Matrix-M arm; Cells arranged as grp1=control: a=73, b=1436-73=1363; grp2=R21: c=73, d=2917-73=2844; The paper's p came from a comparison of these two proportions, approximated here by Pearson chi-square on the 2×2 tableMethod: Two-sided Pearson chi-square on the 2×2 table via pChi2x2.How we recomputed it: pChi2x2(73,1363,73,2844) - CONSISTENTreported p = .001 · recomputed p = .001Reviewer 2Recompute two-sided Pearson chi-square p for 18-month seasonal-site asymptomatic parasitaemia (control 32/718 vs R21 29/1444) and compare with reported p=0.0014.
“At 18 months at the seasonal sites, 32 (4·4%) of 718 participants in the control group had asymptomatic parasitaemia compared with 29 (2·0%) of 1444 participants in the R21/Matrix-M group (p=0·0014, ).”
How we recomputed it: pChi2x2(32,686,29,1415)
Overstated conclusions
None foundConclusions that reach past what the paper's own results support — including a significance claim that no longer holds when the statistic is recomputed, and efficacy resting on an unvalidated surrogate endpoint.
Checked — nothing surfaced.
7 major claims checked against the paper's own evidence: all adequately supported.
- supportedReviewer 1R21/Matrix-M vaccine was well tolerated.The paper presents safety data showing that adverse events were mostly mild to moderate, with no treatment-related deaths, and similar rates of serious adverse events between groups.Evidence: Results on solicited and unsolicited adverse events, serious adverse events, and deaths.
“R21/Matrix-M vaccine was well tolerated, with injection site pain (301 [18·6%] of 1615 participants) and fever (754 [46·7%] of 1615 participants) as the most frequent adverse events.”
Abstract ¶2Find in source - supportedReviewer 112-month vaccine efficacy was 75% at seasonal sites and 68% at standard sites.The primary analysis provides these estimates with 95% CIs and p-values, supported by Kaplan-Meier curves and sensitivity analyses.Evidence: Table 2, Figure 2, and text.
“12-month vaccine efficacy was 75% (95% CI 71–79; p<0·0001) at the seasonal sites and 68% (61–74; p<0·0001) at the standard sites for time to first clinical malaria episode.”
Abstract ¶3Find in source - supportedReviewer 1Vaccine efficacy against multiple clinical malaria episodes was 75% at seasonal sites and 67% at standard sites.The secondary analysis using Cox regression with robust standard errors confirms these estimates.Evidence: Table 2, all episodes section.
“Similarly, vaccine efficacy against multiple clinical malaria episodes was 75% (71–78; p<0·0001) at the seasonal sites and 67% (59–73; p<0·0001) at standard sites.”
Abstract ¶3Find in source - supportedReviewer 1A modest reduction in vaccine efficacy was observed over the first 12 months.Post-hoc analysis by 3-month periods shows declining efficacy from 80% to 67% at seasonal sites, with a statistically significant trend.Evidence: Table 3 and text.
Efficacy declined over the first year, from 80% (95% CI 76–84) in months 1–3 to 67% (55–76) in months 10–12 in the seasonal sites.
Results ¶7reviewer’s wording - supportedReviewer 1Vaccine-induced antibodies against the NANP repeat correlated with vaccine efficacy.The paper reports that NANP-specific IgG titres were measured and that higher titres were associated with lower risk of clinical malaria, with a dose-response relationship by tertile.Evidence: Results, paragraph 13 and Figure S4 (not shown, but referenced).
“Vaccine-induced antibodies against the conserved central Asn-Ala-Asn-Pro (NANP) repeat sequence of circumsporozoite protein correlated with vaccine efficacy.”
Abstract ¶3Find in source - supportedReviewer 1Higher NANP-specific antibody titres were observed in the 5–17 month age group, and this group had the highest 12-month vaccine efficacy.The paper shows that the younger age group had significantly higher antibody titres and higher efficacy (79% at seasonal sites) compared to the older age group.Evidence: Results, paragraphs 8 and 13.
“Higher NANP-specific antibody titres were observed in the 5–17 month age group compared with 18–36 month age group, and the younger age group had the highest 12-month vaccine efficacy on time to first clinical malaria episode at seasonal (79% [95% CI 73–84]; p<0·001) and standard (75% [65–83]; p<0·001) sites.”
Abstract ¶3Find in source - supportedReviewer 1R21/Matrix-M could be widely deployed and a very important addition to help prevent malaria.The Discussion summarises the high efficacy, safety, low cost, and large-scale manufacturing capacity, which support this conclusion.Evidence: Discussion, final paragraph.
“Overall, R21/Matrix-M could be widely deployed and a very important addition to help to prevent malaria.”
DiscussionFind in source
Efficacy claim is anchored to an adequate endpoint and a meaningful effect.
- ADEQUATESurrogate endpointThe primary efficacy claim is based on reduction in clinical malaria episodes (fever plus P. falciparum parasitaemia >5000/μL), which is a clinical outcome, not a surrogate. NANP-specific antibody titres are reported as a correlate but not as the primary basis for efficacy.
“12-month vaccine efficacy was 75% (95% CI 71–79; p<0·0001) at the seasonal sites and 68% (61–74; p<0·0001) at the standard sites for time to first clinical malaria episode.”
- ADEQUATEEffect sizeThe reported vaccine efficacy of 75% at seasonal sites and 68% at standard sites is large, statistically robust, and clinically meaningful, with absolute rate reductions of 868 and 296 cases per 1000 child-years respectively.
“A rate reduction of 868 (95% CI 762–974) cases per 1000 children-years at seasonal sites and 296 (231–362) at standard sites occurred over 12 months.”
Data authenticity concerns
None foundAn adversarial read for patterns associated with data that may not be genuine: results that look too clean, implausibly large effects, duplicated data or images, and methods that do not match the results reported.
Checked — nothing surfaced.
Reporting gaps
2 findings · worst highRequired detail the manuscript never states — study design, biological variables, ethics approval and consent, key resources, statistical reporting, data and code availability, and overall transparency.
- Statistical reporting gaps (tests, assumptions, effect sizes)Assessed
- Ethics/consent reporting incompleteAssessed
The introduction cites the RTS,S/AS01 phase 3 trial and its limitations (e.g., limited supply, waning efficacy), and the phase 2b R21/Matrix-M trial showing high efficacy. It then explains how this phase 3 trial addresses gaps by evaluating a broader age range and multiple transmission settings. The premise is well-rationalised, and limitations of prior work (e.g., small sample, single-country) are explicitly addressed through the trial design.
“In the phase 3 trial of RTS,S/AS01, a circumsporozoite protein-based vaccine, vaccine efficacy in children aged 5–17 months with a four-dose regimen was 56% over 1 year and 36% over 4 years.”
“We previously reported 24 month efficacy of 75% and 77% for time to first episode and multiple episodes of clinical malaria, respectively, with four doses of R21/Matrix-M in children aged 5–17 months at enrolment in Nanoro, Burkina Faso, in a phase 2b study.”
“In this multicentre, double-blind, randomised, phase 3 trial, we aimed to assess the safety and efficacy of R21/Matrix-M vaccine in the extended age range of 5–36 months of age at the first dose, rather than from 5–17 months.”
“In the phase 3 trial of RTS,S/AS01, a circumsporozoite protein-based vaccine, vaccine efficacy in children aged 5–17 months with a four-dose regimen was 56% over 1 year and 36% over 4 years.”
“We previously reported 24 month efficacy of 75% and 77% for time to first episode and multiple episodes of clinical malaria, respectively, with four doses of R21/Matrix-M in children aged 5–17 months at enrolment in Nanoro, Burkina Faso, in a phase 2b study.”
“However, the initial supply of this four-dose vaccine (18 million doses over 3 years) is insufficient for coverage of all children born in regions with moderate-to-high malaria transmission (over 25 million children annually).”
The trial uses a double-blind, 2:1 randomised design with an electronic interactive web response system, stratified by site, age, and sex. Blinding covers participants, families, investigators, laboratory teams, and local study team. A priori power calculations are given for seasonal and standard sites. Inclusion and exclusion criteria are listed, and the modified per-protocol population is defined. The control is a licensed rabies vaccine. No independent replication is expected for a pivotal phase 3 trial.
“Randomisation was done using an electronic interactive web response system (DiagnoSearch Life, Thane, India). Randomisation was stratified by trial site (seasonal or standard), and potential confounders, including age (5–12 months, 13–24 months, or 25–36 months) and sex (male or female), using block randomisation with variable block sizes.”
“The trial was double-blinded: participants, their families, all investigators, the laboratory teams, and the local study team were all masked to treatment.”
“At the seasonal sites, the expected incidence rate was 0·58 cases per child per year among the 800 control participants which, with 12 months’ follow-up, would give more than 95% power to exclude a lower limit of efficacy of 30% if the vaccine efficacy was at least 50%.”
“Randomisation was done using an electronic interactive web response system (DiagnoSearch Life, Thane, India). Randomisation was stratified by trial site (seasonal or standard), and potential confounders, including age (5–12 months, 13–24 months, or 25–36 months) and sex (male or female), using block randomisation with variable block sizes.”
“The trial was double-blinded: participants, their families, all investigators, the laboratory teams, and the local study team were all masked to treatment.”
“At the seasonal sites, the expected incidence rate was 0·58 cases per child per year among the 800 control participants which, with 12 months’ follow-up, would give more than 95% power to exclude a lower limit of efficacy of 30% if the vaccine efficacy was at least 50%.”
Baseline characteristics are reported in Table 1, including sex, age, weight, and weight-for-age categories. The paper also reports bed net use and seasonal malaria chemoprevention history. For a human trial, species/strain and housing conditions are not applicable. Both sexes are enrolled, so a justification for single-sex is not needed.
“Male | 1607/3103 (51·8%) | 805/1541 (52·2%) | 2412/4644 (51·9%)”
“Age, months | 19·1 (9·0) | 18·9 (9·0) | 19 (9·0)”
The paper names the local ethics committees, University of Oxford, and London School of Hygiene & Tropical Medicine as approving bodies. Written/thumb-printed consent is described. However, no explicit statement of adherence to the Declaration of Helsinki or ICH-GCP is found in the main text; this is a minor reporting omission. The study is registered and ethics approval is documented, so the omission is unlikely to reflect a substantive violation.
“The trial was approved by all the local ethics committees and regulatory authorities, as well as the ethics committees at the University of Oxford (Oxford, UK) and The London School of Hygiene & Tropical Medicine (London, UK), with supportive coordination by the African Vaccine Regulatory Forum.”
“Before screening, parents or guardians of participants provided written or thumb-printed consent, which was verbally re-checked at every study visit.”
“The trial was approved by all the local ethics committees and regulatory authorities, as well as the ethics committees at the University of Oxford (Oxford, UK) and The London School of Hygiene & Tropical Medicine (London, UK), with supportive coordination by the African Vaccine Regulatory Forum.”
“Before screening, parents or guardians of participants provided written or thumb-printed consent, which was verbally re-checked at every study visit.”
R21 (Serum Institute of India), Matrix-M (Novavax AB), and the control rabies vaccine (Abhayrab; Indian Immunologicals) are described with dose and formulation. The statistical software Stata version 17 is identified. No antibodies, cell lines, or organisms were used as research tools, so those sub-criteria are not applicable.
“Participants received R21 (Serum Institute of India) as a two-vial formulation: R21 was mixed immediately before administration with the saponin-based vaccine adjuvant Matrix-M (Novavax AB, Uppsala, Sweden). A dose of 5 μg R21 with 50 μg Matrix-M was used in the trial.”
“A licensed rabies vaccine (Abhayrab; Indian Immunologicals, Hyderabad, India) was the control vaccine.”
“All statistical analyses were performed using Stata version 17.”
“Participants received R21 (Serum Institute of India) as a two-vial formulation: R21 was mixed immediately before administration with the saponin-based vaccine adjuvant Matrix-M (Novavax AB, Uppsala, Sweden). A dose of 5 μg R21 with 50 μg Matrix-M was used in the trial. A licensed rabies vaccine (Abhayrab; Indian Immunologicals, Hyderabad, India) was the control vaccine.”
“All statistical analyses were performed using Stata version 17.”
“IgG antibodies against a polypeptide of six repeats of the central NANP region sequence were measured in the first 50% of participants enrolled at each trial site by a validated ELISA using electrochemiluminescence as a detection technique (Meso Scale Discovery; Rockville, MD, USA).”
Cox regression (stratified by site), log-binomial models, and robust standard errors for multiple episodes are described; effect estimates are consistently reported with 95% CIs; data presentation follows the clinical-trial idiom (trial profile, Kaplan-Meier plots, per-group n). The main limitation is that several key p-values are printed as 'p<0·0001' thresholds, which is a reporting precision issue rather than a detected statistical error.
“The primary analysis was time to first episode of clinical malaria and was analysed by Cox regression stratified by study site (seasonal or standard).”
“The primary analysis was time to first episode of clinical malaria and was analysed by Cox regression stratified by study site (seasonal or standard).”
“All statistical analyses were performed using Stata version 17.”
“12-month vaccine efficacy was 75% (95% CI 71–79; p<0·0001) at the seasonal sites and 68% (61–74; p<0·0001) at the standard sites for time to first clinical malaria episode.”
The paper states that anonymised participant data will be made available upon request with a data access agreement, and that the study protocol is provided in the appendix. No raw data repository deposit or accession numbers are applicable for patient-level data. No custom code is mentioned, so code sharing is not applicable.
“Anonymised participant data will be made available when the trial is complete, upon requests directed to the corresponding author. Proposals will be reviewed and approved by the sponsor, investigators, and collaborators based on scientific merit. After approval of a proposal, data can be shared through a secure online platform after signing a data access agreement.”
“Anonymised participant data will be made available when the trial is complete, upon requests directed to the corresponding author. Proposals will be reviewed and approved by the sponsor, investigators, and collaborators based on scientific merit. After approval of a proposal, data can be shared through a secure online platform after signing a data access agreement. All data will be made available for a minimum of 5 years from the end of the trial.”
“The study protocol is provided in the .”
The CONSORT flow diagram is present (Figure 1), but the paper does not reference the CONSORT checklist. Trial registration is provided (NCT04704830). All pre-specified primary and secondary outcomes are reported, including negative results. Limitations are discussed in the Discussion. Conclusions are proportional and do not overclaim. Funding sources and conflicts of interest are declared.
“This study had some limitations. The trial was not powered to assess vaccine efficacy against clinical malaria at individual sites nor efficacy against mortality or severe malaria across all sites.”
“This trial is registered on ClinicalTrials.gov, NCT04704830 (https://clinicaltrials.gov/ct2/show/NCT04704830) , and is ongoing.”
“This study had some limitations. The trial was not powered to assess vaccine efficacy against clinical malaria at individual sites nor efficacy against mortality or severe malaria across all sites.”
Registered (3 IDs: ClinicalTrials.gov). No reporting guideline cited.
Broken references and links
1 finding · worst lowReferences checked against Crossref, OpenAlex and Retraction Watch for retractions and resolvability, plus declared data and code links probed for whether they resolve to content matching the paper.
- References not resolvable to a published paperRecomputed
Checked 11 references by DOI: 5 verified — 1 DOI unresolved, 5 no DOI (shown, not verified).
- UNRESOLVED10.1101/19009282v1.fullPhase I assessments of first-in-human administration of a novel malaria anti-sporozoite vaccine candidate, R21 in matrix-M adjuvant, in UK and Burkinabe volunteersCited DOI does not resolve to any Crossref record.
- NO DOIWorld malaria report 2022No DOI in the reference — shown for manual review; not independently verifiable (not a fabrication signal).
- NO DOIFull evidence report on the RTS.S.AS01 malaria vaccineNo DOI in the reference — shown for manual review; not independently verifiable (not a fabrication signal).
- NO DOIFirst malaria vaccine supply allocations May 2023No DOI in the reference — shown for manual review; not independently verifiable (not a fabrication signal).
- NO DOIFramework for the allocation of limited malaria vaccine supplyNo DOI in the reference — shown for manual review; not independently verifiable (not a fabrication signal).
- NO DOIHigh level efficacy in humans of a next-generation Plasmodium falciparum anti-sporozoite vaccine: R21 in Matrix-M (TM) adjuvantNo DOI in the reference — shown for manual review; not independently verifiable (not a fabrication signal).
3 data/code links checked; 3 live.
- datahttps://clinicaltrials.gov/ct2/show/NCT04704830LIVEHTTP 200Resolves, but the content could not be matched to the paper.
- datahttps://clinicaltrials.gov/ct2/show/NCT05155579LIVEHTTP 200Resolves, but the content could not be matched to the paper.
- datahttps://clinicaltrials.gov/ct2/show/NCT05385510LIVEHTTP 200Resolves, but the content could not be matched to the paper.
Copyediting
1 finding · worst lowWording, consistency and formatting errors that need correcting before submission.
- Wording or formatting errors that need correctingAssessed
10 copyedit issues flagged (1 major): mostly consistency, typo, punctuation.
- MAJORconsistencyDiscussion“the primary analysis shows vaccine efficacy against clinical malaria of 75% (72–79) at seasonal sites and 67% (59–73) at standard sites across the entire cohort aged 5–36 months over 12 months”→ Align with Abstract/Results: 75% (71–79) at seasonal sites and 68% (61–74) at standard sites.
- MINORtypoAcknowledgments“and also recevied funding from the Wellcome Trust”→ and also received funding from the Wellcome TrustSpelling error: 'recevied' should be 'received'.
- MINORtypoMethods, Study design and participants“Coastt”→ CoastDuplicate 't' in 'Coastt' should be 'Coast'.
- MINORconsistencyTable 2, East African sites all episodes row“292 (78’3%)”→ 292 (78.3%)An apostrophe is used instead of a decimal point; should be a period.
- MINORtypoAcknowledgments“also recevied funding from the Wellcome Trust”→ Change 'recevied' to 'received'.
- MINORtypoMethods, Study design and participants“Kenya Medical Research Institute Centre for Geographical Medicine Research–Coastt”→ Remove the extra 't' → 'Coast'.
- MINORconsistencyResults, Serious adverse events“with 77 male participants and 64 female participants reporting a serious adverse event”→ Clarify the total participant count: 77 + 64 = 141, but the text states 129 participants had SAEs.
- MINORconsistencyAbstract vs Results“From April 26, 2021, to Jan 12, 2022, 5477 children consented to be screened”→ Use one screening start date throughout; Results says April 14, 2021.
- MINORpunctuationTable 2, East African sites“292 (78’3%)”→ Replace the right single quotation mark with a decimal point: '78·3%'.
- MINORpunctuationTable 2, Kilifi site“0.37 (69/185·0)”→ Use a consistent decimal separator: '0·37 (69/185·0)'.
The published paper is methodologically robust, but an informed reader should note three issues: (1) the absence of a Declaration of Helsinki compliance statement, though ethics approval is documented; (2) the reporting of p-values only as thresholds rather than exact values; and (3) several internal consistency errors (efficacy numbers in Discussion, SAE counts, screening date) that warrant a correction. None of these undermine the main conclusions, but they should be addressed in a corrigendum.
- 1.HIGHcopyeditCorrect the primary efficacy numbers in the Discussion to match the Abstract and Results: 75% (71–79) at seasonal sites and 68% (61–74) at standard sites.This is a major inconsistency that could mislead readers and may require a formal correction.
- 2.HIGHcopyeditReconcile the serious adverse event participant count: 77 male + 64 female = 141, but the text states 129 participants had SAEs.The discrepancy suggests a reporting error in the number of participants with SAEs.
- 3.HIGHcopyeditCorrect the screening start date discrepancy between Abstract (April 26, 2021) and Results (April 14, 2021).Inconsistent dates undermine the perceived accuracy of the paper.
- 4.HIGHcopyeditClarify the denominator discrepancy in the modified per-protocol R21/Matrix-M group: 3103 in text vs 3102 in Table 2.A clear denominator is essential for interpreting vaccine efficacy calculations.
- 5.HIGHethicsAdd an explicit statement of compliance with the Declaration of Helsinki or ICH-GCP in the Ethics section.This is a standard requirement for clinical trials and its absence is a reporting gap.
- 6.HIGHotherVerify the preprint reference 'Phase I assessments... R21 in matrix-M adjuvant' (DOI: 10.1101/19009282v1.full) which was not found in the registry; ensure it is correctly cited or replace with a published version.An unresolved reference may be a fabrication signal and should be validated.
- 7.MEDIUMstatisticsReplace threshold p-values (e.g., p<0.0001) for primary and key secondary efficacy endpoints with exact values to 2-3 significant figures, or provide exact values in the appendix.Threshold p-values are imprecise reporting and hinder meta-analysis or independent verification.
- 8.MEDIUMreportingAdd a statement referencing a reporting guideline (e.g., CONSORT) and submit the completed checklist as a supplement.Explicit reference to a reporting guideline is standard practice for clinical trials.
- 9.LOWcopyeditCorrect the typo in the Acknowledgments: 'recevied' to 'received'.Minor spelling error reduces professionalism.
- 10.LOWcopyeditCorrect the typo in Methods: 'Coastt' to 'Coast'.Minor spelling error in a location name.
- 11.LOWcopyeditCorrect the decimal separator in Table 2 for East African sites: '78’3%' to '78.3%' or '78·3%'.Inconsistent decimal separators could cause confusion.
- 12.LOWreportingConsider adding baseline comorbidity prevalence and, if collected, ethnicity/race to Table 1, or state that these were not collected.Complete demographics enhance the generalisability assessment.
- 13.LOWstatisticsIn the Statistical analysis section, note whether the proportional hazards assumption was tested (e.g., using Schoenfeld residuals) or state that the method is robust to non-proportionality.Verification of assumptions adds rigour to the analysis.
The star rating is the report’s one-glance summary. Every paper starts at 5★ and loses stars for the concrete problems the review finds — so a rating is never a vague average, it’s a running total you can read line by line under “How this rating was calculated.”
- Reporting — 8 dimensionseach dimension that fully fails−½★
- each dimension partially met−¼★
- Statistics · Integrity · Claimseach serious problem−1★
- each medium problem−½★
- Citationseach retracted or unverifiable reference−¼★
- Copyeditonly when the manuscript needs a full edit−½★
The rating never drops below 1★, and a demonstrable critical failure (an impossible statistic, a proven ethics violation) caps it at 1★ on its own — so the stars can never look healthy when the verdict is CRITICAL.
The rating draws on a panel of agents. Three independent Kaimen Rigor reviewers grade the eight dimensions below across several independent passes (the shown verdict is their majority vote — steadier than any single run), isolate the paper’s major claims and check its own evidence backs them, and flag integrity concerns. Alongside them, a citation agent resolves every reference against Crossref, OpenAlex, and Retraction Watch; a statistics agent recomputes reported tests; and rule-based checks verify that declared data/code links actually resolve. Full text is required — an abstract-only submission is not analyzed.
Graded against NIH, MDAR, ARRIVE 2.0, CONSORT, EQUATOR, and RRID guidelines. A dimension that doesn’t apply to the study type is skipped, never penalized.
This Kaimen Rigor review is model-assisted and is not a substitute for formal expert review. It complements human evaluation by surfacing potential methodological concerns — verify each finding against the source.