Catching viruses such as Covid 19 from public toilets is possible.
However as long as you wash your hands after wiping your bottom down then there should be no concern about getting the Covid-19 or other viruses or diseases from public toilet seats.
The Covid-19 Viruses does not live very long anyway on hard surfaces such as the toilet seat and most times the Virus of Covid-19 and other viruses will only live 24 hours or even less on hard surfaces.
I always wash my hands or at least use hand sanitizer after using the toilet and after wiping my bottom which you should always do as well.
Even when changing your babies or toddlers diaper you should wash your hands and even wash their hands as well because the baby or toddler sometimes gets poop on their hands.
If your kids use the toilet make sure they wash their hands as well.
I keep baby wipes in my purse when in public to wipe my butt with and wipe my kids butts as well when they use the toilet.
Well my older kids that are out of diapers wipe their own butts with the wipes but the wipes get them cleaned.
I still use the wipes to wipe my youngest sons bottom since he's 3 and still wearing diapers although he's working on potty training.