SOCHI, Russia — Bob Costas returned as host for NBC’s prime-time Olympic coverage Monday night, if still not exactly clear-eyed, at least with a sharpened sense of respect for the colleagues and crew who covered for him during a six-day absence.

Costas joked at the show’s opening that he was “sitting in” for Matt Lauer and Meredith Vieira, who had subbed for him while he was out with an eye infection. He thanked the two, and viewers for expressing concern.

“My apologies to everyone for the unavoidable but uncomfortable circumstance of a broadcaster’s ill-timed affliction getting in the way, even for just a moment, from what we all came here for,” Costas said.

Hours before his return, he told The Associated Press that his infection has to run its course of 2-to-3 weeks, the entire Olympics.