In the 21 collected studies, it was found that COVID-19 patients had significantly higher levels of pooled GFAP (SMD = 0.52; 95% CI: 0.31, 0.73; p ≤ 0.001) and NfL (SMD = 0.60; 95% CI: 0.37, 0.82; p ≤ 0.001) when compared to the healthy controls. The gene discussed is GFAP; the disease is COVID-19.