My manager and the flu

My manager has been away sick for the last two days. His message to our team was oddly worded.

He said that he has "tested positive for flu symptoms." Wouldn't it be sufficient to just say that he has the flu?

I can't tell if he tested for COVID-19 and was negative and used the same sentence construction for the flu or if he is indeed so sick that he can't form a clear sentence.

Last week, we had a department outing. I didn't go due to heel pain. Perhaps he caught the flu from that event?

I hope that he feels better soon. He said that he may or may not be working later on today. We'll see.