The COVID-19 pandemic has revealed substantial heterogeneity in biomarker profiles associated with disease severity. While inflammation-driven responses are implicated in progression to critical illness, the role of nutritional status and micronutrient levels in shaping outcomes remains incompletely understood. This study integrates 35 studies using a multi-visual meta-analytic approach to delineate the relationships between inflammatory biomarkers, nutritional/vitamin markers, and severe COVID-19 outcomes.

We conducted a systematic search of major databases (PubMed/MEDLINE, Embase, and Web of Science) for studies reporting quantitative associations between serum biomarkers and COVID-19 severity or mortality. Data were harmonized to standardized mean differences (SMDs) where possible. A multi-plot synthesis (forest, funnel, volcano, and bubble plots) was employed to capture effect sizes, precision, heterogeneity, publication bias, and variance. Inclusion criteria encompassed adult participants with confirmed SARS-CoV-2 infection who reported inflammatory markers (CRP, IL-6, ferritin), nutritional markers (e.g., albumin, pre-albumin), vitamins (e.g., A, C, D, E), and immune markers, where available. Exclusion criteria included pediatric populations and studies lacking extractable quantitative data.

Across 35 studies, inflammatory biomarkers were consistently elevated in severe COVID-19, with CRP, IL-6, and ferritin showing directionally positive associations with adverse outcomes. Nutritional and micronutrient markers tended to be reduced in severe cases, with albumin and several vitamins (notably vitamin D, C, and E) frequently depleted, though substantial between-study heterogeneity existed. The integrated visualizations revealed concordant signals of inflammation amid variable nutritional statuses, while funnel plots suggested modest small-study effects that did not materially alter the overall conclusions. Sensitivity analyses confirmed robustness of the main inflammation-associated findings and highlighted context-dependent variability for nutritional markers. Collectively, the results underscore a central inflammatory axis in severe COVID-19, modulated by nutritional and micronutrient status, with implications for risk stratification and supportive care strategies.

Our multi-plot synthesis provides a cohesive narrative linking systemic inflammation with adverse outcomes in COVID-19 and delineates nuanced roles for nutritional and vitamin-related factors. These findings support concurrent emphasis on anti-inflammatory management and nutritional optimization in high-risk patients, while also guiding future research to disentangle context-specific moderators and to test targeted nutritional interventions.