Association between serum vitamins and COVID-19 infection: a cross-sectional study of healthcare workers in a Nigerian tertiary hospital

Although the global burden of COVID-19 has significantly decreased, understanding the role of micronutrients in modulating immune responses to SARS-CoV-2, especially among vulnerable populations like the healthcare workers, remains very important. This study assessed the association between serum vitamin levels and COVID-19 infection in this high-risk group in a Nigerian tertiary hospital. A cross-sectional hospital-based study involving 181 apparently healthy healthcare workers with varying degrees of exposure to COVID-19 patients was carried out over a 6-week period in February to March 2022. Data were collected using an interviewer-administered pretested, semi-structured questionnaire. Socio-demographic data and venous blood of all participants were collected for biochemical assay of both fat- and water-soluble vitamins A, D, E, K, and Vitamins B1, B2, B5, B6, B9, B12 and C, respectively, using high-performance liquid chromatography. Data were analysed using IBM IPSS version 25. The prevalence of PCR-confirmed COVID-19 infection was 23.2%. Slightly more than half (99; 54.7%) were below forty years of age. COVID-19 positive individuals had significantly lower mean serum levels of fat-soluble vitamins compared to their COVID-19 negative counterparts, as follows; A (37.31 µg/dL vs. 44.57 µg/dL, p = 0.003), D (42.03 ng/mL vs. 50.59 ng/mL, p = 0.024), and E (0.84 mg/dL vs. 1.01 mg/dL, p = 0.019), and water-soluble vitamins B1 (106.02 nmol/L vs. 136.51 nmol/L, p < 0.001), B2 (52.89 ng/mL vs. 69.56 ng/mL, p = 0.003), B5 (5.54 ng/mL vs. 7.74 ng/mL, p < 0.001), B6 (18.31 ng/mL vs. 25.02 ng/mL, p < 0.001), B9 (11.34 ng/mL vs. 13.92 ng/mL, p = 0.002), and C (0.63 mg/dL vs. 0.78 mg/dL, p = 0.007). Vitamins K and B12 were not significantly different between the two groups. This study identified an association between lower serum levels of fat-soluble vitamins A, D, and E, and most water-soluble vitamins with COVID-19 infection in healthcare workers. While further research is needed, these findings suggest the potential usefulness of micronutrient intervention to reduce vulnerability to COVID-19 and related infections. Not applicable.