We have investigated numerically the ability to inhibit spike protein from SARS-CoV-2 to attach and inter the host cell when exposed to energetic photons. The Geometric Progression fitting method have been adopted to calculate the equivalent atomic number for photon energy absorption (Zeq), exposure and absorption buildup factors in the energy range E∈ [15–300] keV for the S2-subunit in the spike protein. The buildup factors have shown a peak value at adsorption resonance energy between 36–60 eV per amino acid of the S2-subunit which depends on the mean free path of the photon within the protein structure and the type of mutation. The resonance energies (between UV and X-ray range) have been found to depend on the protein molecular composition. This opens the possibility of using energetic photons to break up the S2-subunit into small fragments. Our results may contribute to the continues racing for finding noninvasive technique for medical trials using radiotherapy treatment for the COVID-19 virus.