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Glomerulonephritis before and after BNT162b2 mRNA vaccine rollout: biopsy-based trends, histopathological spectrum,
Meryem Keleş1, Ezgi Coşkun Yenigün2, Aysel Çolak3
1Department of Nephrology, University of Health Sciences, Ankara Bilkent City Hospital, Ankara, Türkiye. kelesmrym@outlook.com.
Introduction:
mRNA-based vaccines developed against the COVID-19 pandemic have been reported to trigger immune-mediated glomerular diseases in rare cases. However, it remains unclear whether these cases have a direct causal relationship with the vaccine or whether they result from the "unmasking" of latent pathologies. This study aims to compare biopsy-based proportions and the histopathological spectrum of glomerulonephritis (GN) before versus after the rollout of the Pfizer-BioNTech (BNT162b2) mRNA vaccine, and to explore temporal associations between vaccination/infection and GN presentation among biopsied patients.
Methods:
In this single-center retrospective cohort study conducted at Ankara Bilkent City Hospital, renal biopsy data from the periods before (April 1, 2020- March 31, 2021) and after (April 1, 2021- March 31, 2022) mRNA vaccination were compared. GN diagnosis rates, subtype distributions, and the temporal relationship between symptom onset and vaccination/infection were analyzed. Logistic regression analyses were performed to identify risk factors for GN development.
Results:
Among patients undergoing native kidney biopsy, the proportion of biopsies yielding GN was higher in the post-rollout period than in the pre-rollout period (70.5% vs 60.2%; biopsy-based OR 1.58, p = 0.026). However, in a temporal-proximity analysis based on the interval from vaccination to biopsy, the GN proportion among patients biopsied within 3 months of vaccination (68.5%) was similar to that of patients biopsied >3 months after vaccination or unvaccinated (67.6%) (OR = 1.04; p = 1.00). In the histopathological spectrum, the proportion of IgA Nephropathy (IgAN) increased from 16.5% to 26.2% (p = 0.040); exploratory subtype analyses suggested higher IgAN odds in the temporally proximate group (unadjusted OR = 2.57; p = 0.0129).
Conclusion:
Our biopsy-based analyses suggest no higher odds of GN among patients biopsied within 3 months of vaccination compared with other biopsied patients, and the observed post-rollout changes may reflect diagnostic awareness and an unmasking phenomenon rather than a direct vaccine effect. The observed increase in IgAN diagnoses warrants further investigation in larger, population-based studies and should be interpreted cautiously given potential confounding and multiple comparisons.