When someone is not well, the last thing they need is a lot of people making a fuss about it. And if someone chooses to keep their health matters to themselves, that's entirely their own choice. No one has a right to know about anyone else's medical condition.
Discussing someone else's heath status in public, and speculating about their ability to do their jobs is insulting, and unnecessarily negative.
On a personal note, last year I went through cancer treatment. Thanks to the excellent work of my hospital, I recovered. I was even able to continue my day job as managing director of a business whilst I was undergoing cytotoxic chemotherapy.
What made this possible for me was the strength, positive thinking and encouragement of my family, friends and colleagues around me, who were open-minded enough to focus on what I could do, rather than on what I could not.
None of us are immune from occasional sickness. All of us need to be given the space to get well, in our own way, and with the help of qualified medical professionals.
If you know someone who is not well, the best way to help them is to focus on the positive, give them the space to tell you as much or as little as they choose, and be open minded about what they are able to achieve.