Cant understand this relative clause

Question

There is this little article that im using to study japanese and one of its passages says:

国立感染症研究所によると、約3000の病院で6月25日までの1週間にヘルパンギーナがうつったことがわかった人は、1つの病院に平均で5.79人いました。今までの10年でいちばん多くなりました。

I cant grammatically understand this part:

ヘルパンギーナがうつったことがわかった人

I understand that all of it is a relative clause modifying 人. I dont understand the grammatical role of ヘルパンギーナがうつったこと.

Is it actually the subject ? How would you write it in a non-relative-clause form?

I'd appreciate it if anyone could give me a grammatical analysis of this specific part.

Answer 1

Before 人 was taken out to be modified by the rest of it, the original sentence would have looked like:

ヘルパンギーナが人にうつったことがわかった。
Herpangina was found to have transmitted (itself) to people.
(lit. The fact that herpangina transmitted (itself) to people was found.)

(I couldn't find a good intransitive verb that would retain the subject-verb-destination relationship between ヘルパンギーナ, うつる and 人 and still convey the meaning more or less accurately.)

This became:

ヘルパンギーナがうつったことがわかった人
the people herpangina was found to have transmitted (itself) to

The particle に got lost in the process.

Answer 2

ヘルパンギーナがうつったことがわかった人

The form of this sentence is:

[Rel clause] + 人

In the relative clause: ヘルパンギーナがうつったことがわかった

こと is the subject which is modified by another relative clause.

分かる in this context means "to be known".

So ヘルパンギーナがうつったことがわかった人 means (considering context)

Literally:

The people for whom it (the fact they contracted herpangina) is known.

Idiomatically:

The known people who contracted herpangina

Consider that this clause is the topic of the sentence (marked by は) and as such it can be interpreted widely depending on what follows. So it could be the number of people, the place where they got infected, an average, etc. In your case,

ヘルパンギーナがうつったことがわかった人は、1つの病院に平均で5.79人いました

The average of known people who contracted herpangina per hospital was 5.79.

• The literally translation may have surpassed my knowledge of English grammar. If so, leave me a comment.

Answer 3

I dont understand the grammatical role of ヘルパンギーナがうつったこと. Is it actually the subject?

It is the subject of わかった, yes.

I infer from context that the うつる verb here is 移る, in the sense of "to be infected/contagious".

Let's understand the entire thing piece by piece:

ヘルパンギーナ -> mouth blisters

ヘルパンギーナがうつった -> mouth blisters infected (someone)

ヘルパンギーナがうつったこと -> the fact of having been infected with mouth blisters (i.e.: こと is a nominalizer here, which is to say a placeholder noun that is described by the relative clause ヘルパンギーナがうつった)

ヘルパンギーナがうつったことがわかった -> being infected with mouth blisters was known

ヘルパンギーナがうつったことがわかった人 -> person who knew about (personally) being infected with mouth blisters

An independent sentence equivalent seems straightforward: 人はヘルパンギーナがうつったことがわかった, "the person knew about being infected with mouth blisters". (Of course, this still contains its own relative clause. Rather than nominalizing that, I suppose we could use quotative-と or soemthing.)