Assessment of Kidney and Thyroid Health After COVID-19 Vaccination Among Healthy Adults in Ibadan, Nigeria

Background: SARS-CoV-2 vaccines have demonstrated effectiveness in preventing COVID-19 infection. However, concerns persist regarding potential adverse effects on kidney and thyroid health in certain populations. While the overall safety and efficacy of the available vaccines have been established, limited research has documented post-vaccination complications involving the kidneys and thyroid. Currently, such adverse effects are rarely reported in our environment. This study investigates the impact of SARS-CoV-2 vaccination on kidney and thyroid functions among healthy individuals in Ibadan, Oyo State.  Methodology: This cross-sectional study was conducted with approval from the Oyo State Ethical Board. The participants included a total of 168 healthy individuals, consisting of 82 who had received the SARS-CoV-2 vaccine and 86 who had not, with ages ranging from 18 to 65 years. Sociodemographic information was collected using a structured questionnaire. Blood samples (10 milliliters) were taken to measure serum levels of thyroid-stimulating hormone, free tri-iodothyronine, thyroxine, urea, creatinine, C-reactive protein (CRP), glycated hemoglobin, and SARS-CoV-2 antibodies, employing standard laboratory procedures. The data were analyzed statistically, revealing no significant differences (p > 0.05) between the vaccinated and unvaccinated groups in the mean levels of CRP, glycated hemoglobin, kidney function markers, and thyroid function markers, all of which remained within normal reference ranges.  Results: Both groups exhibited values within normal reference ranges. There were no statistically significant differences in markers of kidney or thyroid function (p > 0.05). C-reactive protein (CRP) levels were lower among vaccinated participants (0.7 ± 0.8 mg/L) compared to controls (1.4 ± 1.7 mg/L), although this difference was not statistically significant. Cystatin-C concentrations were slightly higher in the vaccinated group (0.8 ± 0.2 mg/dL) than in controls (0.7 ± 0.2 mg/dL). Prevalence assessments showed only a small percentage (1.2%) with mild elevations in CRP, FT4, or TSH.  Conclusion: COVID-19 vaccination did not adversely affect renal or thyroid function in apparently healthy individuals. Minor deviations were rare and clinically insignificant, reinforcing vaccine safety.