TMPRSS2-Coagulation Nexus: A Novel Molecular Link Revealed by Pairwise Correlation Analysis Following AstraZeneca (ChAdOx1 nCoV-19) Vaccination in a Nigerian Cohort

Background: While haematological and coagulation changes following AstraZeneca vaccination have been described, the molecular mechanisms linking TMPRSS2 expression to coagulation remain underexplored, particularly in African populations. Methods: In this case-control study, 102 adults (51 vaccinated with AstraZeneca >=6 months prior, 51 unvaccinated controls) aged 18-65 years in Port Harcourt, Nigeria, were evaluated. Full blood count (Sysmex XN-1000), PT/aPTT (Erba Mannheim), RNA concentration, and qRT-PCR for ACE2/TMPRSS2 (normalized to GAPDH) were performed. Pearson correlations and t-tests were conducted (SPSS v26, p<0.05). Results: Because primary between-group comparisons from this cohort have been reported previously, the present analysis focused on correlation patterns. A statistically significant inverse correlation was observed between TMPRSS2 Ct values and activated partial thromboplastin time (aPTT) among vaccinated participants (r = -0.325, p = 0.0202), whereas no corresponding association was detected in unvaccinated controls. Sex-specific differences in TMPRSS2 expression were also observed. No participant reported severe thrombotic or haemorrhagic complications at the time of recruitment. Conclusion: This secondary analysis identified a statistically significant inverse correlation between TMPRSS2 Ct values and aPTT among AstraZeneca-vaccinated individuals. Although causality cannot be inferred, the findings suggest a potential relationship between TMPRSS2 expression and haemostatic pathways in the post-vaccination setting. Larger longitudinal studies are required to validate the observation and clarify its biological significance.