The kickoff of the NFL season Thursday with 17,000 fans in the stadium illustrates the nation’s determination to resume its most popular sport in the middle of a pandemic that has already killed nearly 200,000 Americans. … While Major League Baseball and the NBA have played without fans, the Super Bowl champion Kansas City Chiefs were allowed to open the season Thursday night against the Houston Texans at 22% capacity. The remainder of the NFL teams start their seasons Sunday with restrictions that vary by stadium, with some games devoid of fans and others with scaled-back crowd sizes like Kansas City.