The song is really short, so it's easy to try to translate
ぎゅっと君を抱きしめたい
I want to hold you close
きっと君は病気じゃない
Surely you're not sick
もっと強く抱きしめたい
I want to hold you again in a strong embrace
きっと君は一人じゃない
Surely you're not alone
(Personally and from knowledge, I feel "surely" fits きっと more than "maybe", their meanings are similar but きっと has more of a "definitely" meaning than a "maybe" (which is more neutral))
That's my rough translation. Take it as you will, it's vague so the meaning may be difficult to grasp or maybe a difficult pill to swallow
For me, I wonder if the singer simply hopes to be with someone who's feeling ill. I know if I'm sick, I'm told not to touch anything or anyone.
That alone can make one feel lonely. The last line is reminder from the singer that whether you're ill or not, you're certainly not alone
Buuuuuuut, that might be a stretch. Those are my thoughts, there could be more to it I don't realize
That aside, it's definitely neat to hear Tonio in Japanese, especially with a song that's pretty chill like this!