It is such a small sample size, that I think it is dangerous to draw a conclusion either way.  Ideally, contagious players never make it on the field, but if they do, at least it is an outdoor setting, and while a few players make close contact with some other players for brief periods of time, overall the players are fairly spread out across the field.

Of course the way this season has been going, the Broncos may end up being the first case of team-to-team transmission.

Frankly, I have been a little surprised that the league hasn't taken additional steps to minimize team-to-team contact, especially after the game.  They made a big deal about prohibiting jersey swaps before the season, but it seems like there is quite a bit of post-game mingling between the players.  It seems like it would be easy enough to just require everyone to go straight to the locker rooms after the game.