Based on clinical data and laboratory values at the time of the first vaccination, age (−0–411; p < 0.001), diabetes mellitus (−0.256; p = 0.053), and CRP (−0.319; p = 0.015) correlated inversely, and vitamin D (0.361; p = 0.006), positive response to hepatitis B vaccination (0.268; p = 0.042), hemoglobin (0.219; p = 0.098), and serum albumin (0.466; p < 0.001) correlated correspondingly with the detection of anti-SARS-CoV-2 IgG at week 24 (Table 2). Here, CRP is linked to diabetes mellitus.