According to the latest US CDC declarations, Covid infection is largely transmitted by air and not -as previously supposed- by touching objects “polluted” by others. Thus, at least in public gatherings, we should focus more on cleaning the air surrounding participants rather than on disinfecting objects in contact with them. A low-cost method to accomplish it consists in beaming signals at frequencies that are resonant with the intrinsic frequency of the Covid virus. Resonance condition reduces the intensity of the external (ultrasound/microwave) beam to be well below the IEEE standard of safety. The applied frequency bands are easy to cover the known mutant variants of the virus. As we have emphasized in our previous publication(1) , similar techniques have been effective in various flu infections (including their variant avatars) and have also been studied in efforts to ablate cancer cells (without damaging normal cells). Parenthetically, it should be noted that non virus specific methods such as UV light &/or thermal ablation methods pose problems with input power and thus safety.
(1) https://doi.org/10.1080/15368378.2020.1803081; Non-chemical signatures of biological materials: Radio signals from Covid19?, by Y. Srivastava, E. Sassaroli , J. Swain , A. Widom , M. Narain & G. de Montmollin.