Clothing can probably spread fungal infections (e.g. athlete's foot) from person to person.
There's not a lot of evidence that clothing can spread bacterial infections. But Bloomfield et al. quote Gebel et al., who write: "Absence of definite evidence for a health hazard is not equivalent to evidence of absence of risk."
So, indeed, as Bloomfield et al. write, you might want to sanitize your laundry in certain situations. For example:
- if it's full of feces, vomit, or blood, or
- if someone in the home has a fungal infection (e.g. athlete's foot), or
- if you encounter certain other circumstances.
How can you disinfect your laundry?
Edit: COVID addendum
COVID is spread mainly by close contact between people, not through contaminated clothing or any other contaminated object.
Nevertheless, when washing a COVID patient's laundry, it's probably a reasonable precaution to add some activated oxygen bleach. Please see below.