UVB does work but it takes longer than UVC. So long that if you try to use it to disinfect skin, it's likely to give you sunburn before it kills much of the virus.
Contrast Far-UVC (200-235 nm), which kills the virus quickly and yet does not seem to cause skin or corneal damage, despite being more energetic than UVB.
https://www.nationalacademies.org/based-on-science/covid-19-...
Contrast Far-UVC (200-235 nm), which kills the virus quickly and yet does not seem to cause skin or corneal damage, despite being more energetic than UVB.
https://en.m.wikipedia.org/wiki/Far-UVC