PURPOSE: During COVID-19, significant changes in protein abundance can be linked with disease-related processes. The mass spectrometry-based proteomics of COVID-19-related biomarkers can help with the prognosis and diagnosis of this severe disease. DESIGN: Here, we surveyed scientific works in terms of proteomic analysis of solid tissues and non-blood fluids from COVID-19 patients. Works published since 2022 to date have been covered. RESULTS: Brain, lymph nodes, heart, spleen, aorta walls, liver, adrenal gland and kidneys were investigated as solid organs/tissues. The non-blood fluids involved exhaled breath particles, airway mucus, saliva, swabs, colostrum/milk and urine. The provided table depicts studies/experimental platforms to analyse COVID-19-related candidate protein biomarkers. CONCLUSION: Even eminent research input has been made in this field, continuation towards deeper findings should be made. Translation of proteomics into the clinics to help with diagnostics and therapeutical strategies, is a highly important task. The analysed candidate protein biomarkers are the perspective molecules for pending clinical decisions making and treatments.