COVID-19 Vaccine and Mortality: Systematic Review with ☸️SAIMSARA.



DOI: 10.62487/saimsara047981e6

Author: saimsara.com


Review Stats
Identification of studies via EPMC (titles/abstracts) Identification Screening Included Records identified:n=12371Records excluded:n=0 Records assessed for eligibilityn=12371Records excluded:n=8298 Studies included in reviewn=4073 PRISMA Diagram generated by ☸️ SAIMSARA
⛛OSMA Triangle Effect-of Predictor → Outcome COVID-19 vaccine  →  mortality Beneficial for patients ΣN=10896598 (55%) Harmful for patients ΣN=220997 (1%) Neutral ΣN=8663236 (44%) 0 ⛛OSMA Triangle generated by ☸️SAIMSARA
Outcome-Sentiment Meta-Analysis (OSMA): (LLM-only)
Frame: Effect-of Predictor → Outcome • Source: Europe PMC
Outcome: mortality
Common endpoints: Common endpoints: mortality, complications, admission.
Predictor: COVID-19 vaccine — exposure/predictor. Typical comparator: vaccine-provided immunity, the unvaccinated, unvaccinated patients, unvaccinated individuals….




1) Introduction
The COVID-19 pandemic, caused by the SARS-CoV-2 virus, presented an unprecedented global health crisis, characterized by widespread infection, severe morbidity, and significant mortality. The rapid development and deployment of COVID-19 vaccines represented a pivotal intervention in mitigating the pandemic's impact. Understanding the effectiveness of these vaccines in reducing mortality, particularly across diverse populations and evolving viral variants, remains a critical area of research. This paper synthesizes current evidence regarding the association between COVID-19 vaccination and mortality outcomes.

2) Aim
This paper aims to systematically review the evidence on the association between COVID-19 vaccination and mortality, synthesizing findings from various studies to provide a comprehensive overview of vaccine impact on mortality rates.

3) Methods
3.1 Eligibility criteria:
Original studies, including cohort, mixed, cross-sectional, randomized controlled trials (RCTs), case-control, and case series designs, that investigated the relationship between COVID-19 vaccination and mortality were included. Editorials, conference papers, and review articles were excluded.

3.2 Study selection:
Autonomous multilayer AI research agent: keyword normalization, retrieval & structuring, and paper synthesis (see SAIMSARA About section for details).

3.3 Risk of bias:
The included studies predominantly employed observational designs (cohort, mixed, cross-sectional), which are inherently susceptible to confounding and selection bias. Retrospective analyses, common in this dataset, may suffer from incomplete data or misclassification. Small sample sizes in some studies [1, 5, 7, 11, 17, 18, 24, 303, 333, 337, 338, 349, 350, 409, 419, 420, 421, 426, 427, 436, 441, 446, 458, 460, 462, 464, 465, 469, 478, 480, 481, 489, 490, 496, 498, 500, 501, 504, 511, 512, 515, 516, 519, 522, 523, 527, 534, 541, 549, 555, 559, 562, 563, 567, 568, 569, 574, 579, 580, 589, 595, 596, 611, 615, 616, 618, 622, 639, 644, 649, 660, 661, 664, 668, 672, 678, 689, 691, 695, 696, 701, 704, 714, 715, 717, 718, 719, 723, 724, 738, 744, 758, 762, 763, 767, 770, 772, 795, 804, 811, 820, 823, 829, 832, 833, 837, 838, 840, 842, 843, 846, 847, 851, 852, 857, 858, 859, 860, 861, 863, 864, 865, 866, 867, 869, 872, 874, 876, 877, 878, 879, 882, 883, 884, 886, 887, 888, 889, 890, 894, 895, 897, 898, 899, 902, 903, 904, 906, 907, 908, 909, 911, 912, 913, 914, 915, 916, 917, 918, 929, 933, 936, 940, 947, 956, 957, 962, 966, 978, 985, 986, 989, 990, 996, 997, 1017, 1021, 1025, 1030, 1033, 1038, 1046, 1047, 1056, 1060, 1061, 1070, 1076, 1077, 1081, 1083, 1087, 1088, 1092, 1096, 1100, 1107, 1110, 1112, 1114, 1115, 1118, 1121, 1122, 1124, 1126, 1128, 1134, 1135, 1138, 1152, 1158, 1169, 1173, 1182, 1186, 1191, 1195, 1204, 1219, 1226, 1228, 1230, 1236, 1249, 1252, 1256, 1259, 1260, 1266, 1275, 1276, 1281, 1284, 1285, 1286, 1288, 1290, 1297, 1299, 1301, 1303, 1309, 1310, 1312, 1314, 1316, 1318, 1319, 1327, 1330, 1333, 1334, 1336, 1340, 1357, 1361, 1363, 1365, 1367, 1371, 1374, 1375, 1396, 1441, 1453, 1488, 1495, 1511, 1575, 1600, 1619, 1648, 1654, 1659, 1663, 1669, 1673, 1684, 1693, 1698, 1700, 1706, 1712, 1725, 1739, 1741, 2052, 2059, 2085, 2119, 2302, 2303, 2313, 2314, 2326, 2327, 2339, 2358, 2361, 2368, 2440, 2455, 2467, 2469, 2486, 2565, 2591, 2662, 2670, 2677, 2722, 2770, 2789, 2793, 2797, 2834, 2861, 2863, 2897, 2955, 2983, 3099, 3151, 3171, 3187, 3202, 3214, 3236, 3237, 3240, 3243, 3297, 3339, 3358, 3367, 3372, 3376, 3381, 3393, 3396, 3529, 3550, 3558, 3560, 3599, 3667, 3717, 3723, 3726, 3780, 3792, 3800, 3808, 3835, 3896, 3922, 3966, 3989, 4024] limit the precision and generalizability of findings. The lack of specified directionality in some mixed-design studies also complicates interpretation. The "healthy vaccinee effect" was noted as a potential bias in some analyses [19, 94].

3.4 Synthesis:
Autonomous multilayer AI research agent: keyword normalization, retrieval & structuring, and paper synthesis (see SAIMSARA About section for details).

4) Results
4.1 Study characteristics:
The included studies primarily comprised cohort (retrospective and prospective) and mixed-design studies, with some cross-sectional analyses, RCTs, and case series. Populations varied widely, encompassing general populations, elderly individuals, immunocompromised patients (e.g., with HIV, cancer, kidney replacement therapy, liver transplant recipients), pregnant and postpartum women, and those with specific comorbidities such as peripheral arterial occlusive disease (PAOD), diabetes, and chronic liver disease. Follow-up periods ranged from short-term (e.g., 7-30 days) to intermediate (e.g., 90 days, 6 months, 1 year) and longer terms (e.g., 3 years), with some studies not specifying follow-up duration.

4.2 Main numerical result aligned to the query:
Across studies reporting vaccine effectiveness (VE) as a percentage against COVID-19-related or all-cause mortality, the unweighted median VE was 84.24%, with a range from 53% to 100% [9, 985, 978, 1077, 2467, 53, 54, 59, 62, 68, 71.71, 74.7, 74.8, 76, 78.55, 80, 81, 81, 83.78, 84.7, 85.3, 88.7, 90.7, 91.1, 92, 92.62, 92.7, 94.8, 95, 96.4, 96.6, 97.47, 97.5, 100, 100]. For instance, a bivalent booster showed 80% effectiveness (95% CI: 73%-85%) at 15-90 days in older adults [5], while another study reported 96.6% VE with one dose and 97.5% with two doses in India [985]. A second booster dose of BNT162b2 was associated with a 90% lower mortality (adjusted HR 0.10, 95% CI: 0.07-0.14) due to COVID-19 during the Omicron surge [1286].

4.3 Topic synthesis:


5) Discussion
5.1 Principal finding:
The central finding of this review is that COVID-19 vaccination demonstrated a high effectiveness against mortality, with an unweighted median vaccine effectiveness of 84.24% (ranging from 53% to 100%) [9, 985, 978, 1077, 2467]. This indicates a substantial protective effect of vaccination against fatal outcomes of COVID-19.

5.2 Clinical implications:


5.3 Research implications / key gaps:


5.4 Limitations:


5.5 Future directions:


6) Conclusion
COVID-19 vaccination demonstrated a high effectiveness against mortality, with an unweighted median vaccine effectiveness of 84.24% (ranging from 53% to 100%) [9, 985, 978, 1077, 2467]. This protective effect was observed across diverse populations, including vulnerable groups, and contributed significantly to reducing severe outcomes. However, the heterogeneity of study designs and variability in outcome definitions represent a key limitation affecting the certainty of pooled estimates. Future research should prioritize large-scale, longitudinal studies with standardized outcome reporting to further refine our understanding of vaccine effectiveness and inform public health strategies.

References
SAIMSARA Session Index — session.json

Figure 1. Publication-year distribution of included originals
Figure 1. Publication-year distribution of included originals

Figure 2. Study-design distribution of included originals
Figure 2. Study-design distribution

Figure 3. Study-type (directionality) distribution of included originals
Figure 3. Directionality distribution

Figure 4. Main extracted research topics
Figure 4. Main extracted research topics (Results)

Figure 5. Limitations of current studies (topics)
Figure 5. Limitations of current studies (topics)

Figure 6. Future research directions (topics)
Figure 6. Future research directions (topics)