My daughter is a basketball player. Every day her white school uniform is soaked in mud and sometimes she's even wet in rain when she's back home. I immediately tell her to take a shower with Dettol antiseptic soap and soak her uniform in washing powder plus some drops of Dettol liquid antiseptic.

What else can I do to keep my child germ free?

Ask her to take a lukewarm shower and use Savlon soap Or Dettol soap. Keep her immunity built up.; Read this.
Boost Your Immunity During Monsoons

You can give her honey..It boosts immunity.Also add garlic in sabzis..Turmeric is also antibacterial.