I have only been to the shops, so no real idea of how or when
At a guess, when you went to the shops?
There is no way to completely clean or quarantine anything unless you have a hospital grade sterile door lock, and scrub like a surgeon before and after touching anything.
Precautions will reduce your chances of catching anything, but not eliminate it completely.
When you clean your delivery, for example, you have to touch it to clean it. Bring your hand near your face, even in gloves, and bingo....
I worked in a sterile cell culture for years. We had high flow hoods, uv light sterilisers, chlorox bleach to clean everything, everything was autoclaved, hands washed with 100% alcohol....
It still wasn’t a big surprise when a virus, bacteria or fungus got in and contaminated everything. It only takes one cell...