1158. Immunogenicity of COVID-19 vaccine four-dose series in healthy community dwelling adults 50 years and above: interim analysis from the ‘PRospEctiVe EvaluatioN of immuniTy after COVID-19 vaccines’ (PREVENT-COVID) study
Bibliographic record
Abstract
Abstract Background Adults aged > 50 years are at increased risk for severe coronavirus disease 2019 (COVID-19). This study evaluated immunogenicity of COVID-19 vaccines in healthy adults aged > 50 years through quantification of antigen specific antibody concentration and function post-vaccination with two, three and four COVID-19 vaccine doses. Methods Eighty-four immunocompetent, community-dwelling adults 50 to 83 years old (median age 61 years) were enrolled. We measured index virus spike protein (S) specific antibody responses to mRNA (mRNA-1273 or BNT162b2) and/or ChAdOx1-S COVID-19 vaccines. Participants were separated into three groups: (1) mRNA/mRNA/mRNA/mRNA; (2) ChAdOx1-S/mRNA/mRNA; (3) ChAdOx1-S/ChAdOx1-S/mRNA. Responses were quantified via: anti-S IgG geometric mean concentrations (GMCs) (binding antibody units [BAU]/mL), total relative IgG avidity index (TRAI) (avidity units, AU) collected up to one, four, and seven-months after each dose. One-way ANOVA, Tukey-Kramer post-hoc compared groups and Welch’s t-test compared timepoints. Results At one month post-dose two, mRNA/mRNA (1137 BAU/mL, p = 0.0003) and ChAdOx1-S/mRNA (1388, p < 0.0001) had higher anti-S IgG GMCs compared with ChAdOx1-S/ChadOx1-S (195 BAU/mL). However, TRAI was similar amongst the three groups (all p > 0.05); mRNA/mRNA (70 AU), ChAdOx1-S/mRNA (66 AU) and ChAdOx1-S/ChAdOx1-S (58 AU). S-IgG GMCs at one month post-dose three were higher for mRNA/mRNA/mRNA than ChAdOx1-S/ChAdOx1-S/mRNA (1316 vs. 569 BAU/mL p = 0.0162). Similar to post-dose two, post-dose three there were no significant differences in TRAI between groups (all p > 0.05); mRNA/mRNA/mRNA (95 AU), ChAdOx1-S/mRNA/mRNA (98 AU), ChAdOx1-S/ChAdOx1-S/mRNA (101 AU). For mRNA/mRNA/mRNA participants, a fourth mRNA vaccine dose increased S-IgG GMCs at one-month post-dose four compared with one month post-dose two (2825 vs. 1137 BAU/mL, p = 0.0126) and maintained TRAI between timepoints (71 vs. 70 AU, p = 0.9877). Conclusion mRNA vaccines are more immunogenic compared to ChAdOx1-S with regards to S-specific antibody concentration. mRNA boosters maintained antibody avidity. Together, TRAI and anti-S IgG GMCs should be further evaluated when recommending additional booster doses and considered when determining protection against COVID-19. Disclosures Sofia R. Bartlett, PhD, Abbvie: Advisor/Consultant|Abbvie: Grant/Research Support|Cepheid: Advisor/Consultant|Gilead: Advisor/Consultant|Gilead: Grant/Research Support Manish Sadarangani, BM BCh, FRCPC, DPhil, GlaxoSmithKline: Grant/Research Support|Merck: Grant/Research Support|Moderna: Grant/Research Support|Pfizer: Grant/Research Support|Sanofi Pasteur: Grant/Research Support|Seqirus: Grant/Research Support|Symvivo: Grant/Research Support|VBI Vaccines: Grant/Research Support
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.002 | 0.002 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 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 source (direct Gemma or distilled Codex), 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".