They clearly haven't done a good job of stopping people from socialising with other fighters, judging by the video, but Werdum tested negative. You either have it or you fucking don't, people are confusing 'showing symptoms' with having the virus. If the virus isn't in your blood/system today, you do not have covid19 today. The 'symptoms' show after 7days if at all, but the virus is in you from the very first day you have it. Werdum has not caught covid19 from Jacare, nor has any other fighter on the card or it would be present in their blood right now.
There have been confirmed studies from much more qualified scientists than anyone on here, on how you catch covid19. You catch it from being in sustained 'contact' with someone who has it, by that, I mean living with them, working with them for 7hours a day, sharing public transport with them for time. You are highly unlikely to catch covid19 from someone you have passing contact with in a supermarket, or passing in the street within 4-5 feet of them for a few seconds unless they are coughing their guts up.
People have been successfully brainwashed into believing that this virus can be transmitted simply by breathing the same air as someone in general. If this was true, supermarkets wouldn't be open and the lockdown would literally consist of having our doors welded shut like in China. Stop being so fucking afraid. I seriously worry about the mental well-being of a lot of people after this ends, because returning to the real world is not going to be an option - we're going to have 100s of thousands of people on strong medication and job support/welfare money because they are afraid of going outside.