Peroxide can be pretty caustic too. I use bleach for cleaning....kills everything and it dissipates. Acid based solution like vinegar needs to saturate bacteria for at least two minutes to be effective. I wouldn't mix any of these solutions together.
IMO nothing kills germs as well as bleach. It soaks into wood as well, then guess what, it evaporates. Given time it is gone..which is why you have to keep adding it to swimming pools. It is caustic however and so are the initial fumes...but it sure does eliminate all viruses and bacteria.and...
Well, that's kind of why I recommend pressure washing as well as thorough exposure to ultraviolet light. People are reusing all sorts of century old wood these days, I have reused wood that's laid outside in the weather as well. See the coop thread on ventilation too....hopefully these posts...
Sure, wood can harbor parasites, even microscopic ones. Pressure wash the old wood and let it dry thoroughly in the sun. Ultraviolet light kills most things. The you can seal it.