Immunogenicity and Safety of ChAdOx1 nCoV-19 (AZD1222) as a Homologous Fourth-Dose Booster: A Substudy of the Phase 3 COV003 Trial in Brazil
Bibliographic record
Abstract
Objective: To address that, despite widespread use of ChAdOx1 nCoV-19 (AZD1222) as a COVID-2019 booster, fourth-dose clinical outcomes data are limited. We report immunogenicity and safety for ChAdOx1 nCoV-19 as a homologous fourth-dose booster. Participants and Methods: viral particles). All fourth doses were administered to substudy participants between August 18 and October 28, 2022. The data cutoff was December 9, 2022. The primary immunogenicity outcome was noninferiority of ancestral severe acute respiratory syndrome coronavirus (SARS-CoV)-2-neutralizing antibody responses 28 days after dose 4 versus dose 3. Solicited and unsolicited adverse events were recorded 7 and 28 days postdose 4, respectively. Results: 172 participants received a fourth dose (median interval postthird dose, 10.7 months). Ancestral SARS-CoV-2-neutralizing antibody titers postdose 4 were noninferior to those postdose 3; geometric mean fold rise was 1.9 (95% CI, 1.6-2.4; n=112). Immunogenicity results were consistent across all variants analyzed. Local and systemic solicited adverse events were reported in 60.3% (n=35/58) and 43.1% (n=25/58) of participants, respectively. Conclusion: Immune responses after a fourth dose of ChAdOx1 nCoV-19 were noninferior to those after a third dose across SARS-CoV-2 variants. The fourth dose was well tolerated with no emergent safety concerns, supporting the continued development of the ChAdOx1 platform in preparation for future pandemics. Trial Registration: clinicaltrials.gov Identifier: NCT04536051.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.005 | 0.013 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.001 | 0.003 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".