All scientific results are positive, but I have the feeling people end up skewing their research just to show what they want to see. Yesterday I read a study [1] by the most renown Brazilian university claiming that the control of Covid on Brazilian football is bad because 11% of the players got it while in Germany only 0.5% were sick. Then I looked the data up and the Bundesliga has the exact same 11% [2], but the researchers chose a very specific time frame in which they didn't have many cases, just to "prove" their point.
This was easy to verify, but I wonder how many long term researches find gibberish results and no one will ever know.
[1] https://globoesporte.globo.com/sp/futebol/campeonato-paulist...
[2] https://www.sport1.de/fussball/bundesliga/2021/02/bundesliga...