Vicks also does a hand cleaner gel called First Defence – non alcoholic so it doesn’t dry out your skin – that’s claimed to leave a microbe/virus killing residue on your hands that’s active for up to five hours after application, mate of mine who works in the NHS swears by it. Not expensive on eBay in boxes of eight.
Other than that and keeping hands away from mouth, eyes, food etc, avoid other people for an hour or so after hard training sessions as there’s evidence that purports to show that your immune system is temporarily weakened then. Wash hands when you come in from shopping etc.
Tbh, if you’re cohabiting with someone who works with kids, you’re pretty much doomed unless you slather them all over in the First Defence gel as soon as they walk through the front door, in which case colds are likely to be the least of your worries.
Zinc supplements are supposed to prop up the immune system, ditto glucosamine.