Depends on what you are dealing with and what side effects you are willing to accept:
For example Colloidal silvers made with hydroxides or HCL cause your hair to fall out, the ones made with Peroxides cause premature gray hair, the ones with chlorides kill cells on contact, the onew with nitrates cause argyria.
The best kind is the one that is Laboratory Tested by the worlds largest Envioromental Testing Facility ALS Lab.
You can do an internet search for colloidal silver 3000 to 18000 PPM, it is made with Silver ATOMS which are 250,000,000 times smaller than a nanoparticle. This means rapid penetration through the viruses own cell membranes.
NO chemicals are used or added from start to finish guaranteed, you only have plain silver and distilled water.
My couisn had TB and got rid of it in 30 days, I used it to kill fungus on my feet, what caught my attention was some You Tube videos showing how this product killed mosquito larvae and fungus in stale water.
If you want effectiveness this is the way to go.