The question is, how are they getting it (not how do we believe they are getting it) and what can be done about it?
This kind of thinking is sadly lacking IMHO.
Many others and I have theorized a very logical mode (aerosol) of transmission. We may not be correct, but nothing we know thus far precludes the possibility.
...what can be done about it?
Current protocol isn't working! Many others and I believe that a filter/cartridge breathing apparatus is possibly not be enough and that a hazmat suit with self-contained air source may be appropriate for health workers.