Sinner’s Aus coach Cahill revealed he caught same “bug” that swept through team: “I’m crook now, I picked it up from [Sinner]. His other coach was really crook 2 days after he was crook. We’ve all been through it”

Sounds like v infectious respiratory virus

https://www.news.com.au/sport/tennis/darren-cahill-has-revealed-how-close-jannik-sinner-came-to-pulling-out-of-the-australian-open/news-story/ee14095b1fef206990ad286d9da7326b