Is "warded" correctly used?

No.

I’d say treated.

In your sentence, “admitted to” would mean they are now in the hospital.

Thanks, PUNKEY and Borat Sister!

Am I right to say "warded" is the wrong word?

It’s not wrong. In fact it’s quite correct. However, it’s also very archaic, people don't use terms like that anymore which is why it sounds strange.

If I came across the phrase in a book by Jane Austen or William Makepeace Thackeray I would think nothing of it.

I’d say yes, it’s wrong.

ward
[wɔːd]
VERB
warded (past tense) · warded (past participle)
SE ASIAN
admit to or care for in a hospital ward.
"the last of the accident victims was warded"
synonyms:
admit to hospital · admit · take in · let in · accept · receive · give entry to


It looks like it's used in Asia, but not commonly anywhere else.

I decided to use google before I made a pronouncement.

That’s a thing with a global language, words are adopted and discarded locally which is why we all talk differently.

I was watching John Oliver last night and he has something in common with Adam Hills. When Oliver impersonates someone from the UK he puts on an “English” accent despite being English. When Adam Hills impersonates someone else from Australia he also puts on an “Australian “ accent.

I’d change my reply from “treated” to “admitted”.

Admission is the actual process of getting into a hospital for a stay to treat something

What audience are you writing for tanquatlay?

No particular audience.

But what country? British English is different from US, for example

I prefer British English.