There are much better 'disinfectants': alcohol is good at killing living cells, but doesn't do a great job killing spores or penetrating into protein-rich....gunk.

You would probably want to use a "high-level disinfectant" or "sterilant" instead. Gluteraldyhde is fairly common choice or ethylene oxide gas, though both can be fairly nasty if not handled carefully (which is, of course, the whole point).

More emphatically: do not trust alcohol at any concentration to kill pathogens. (Likewise, freezing.)

The way alcohol swaps are used, they move contaminants away from the needle insertion site, and the alcohol helps to dislodge them. And, of course, it does kill some kinds of pathogen, as does soap.