Each year, the flu leaves many bed-ridden and unable to get to work. And while you might worry about how your co-workers will feel about the time you miss, it's unlikely you'll have to worry about disappointing hordes of fans.
But star athletes do: The virus has changed the course of championships, either in the form of missed opportunities or plays made even more memorable for what players overcame.
"Fans are not forgiving of athletes for being human," said Dr. Rebecca Jaffe, a family and sports medicine physician in Wilmington, Del., speaking of her own experiences with New York- and Philadelphia-area fans.
"They shouldn't put their overall health at risk to do something that will limit or compromise their well-being."
So some athletes make it out to play, while others have their doctors recommend staying home.
"It depends on the severity of it," said Dr. Scott E. Nelson, a family physician in Cleveland, Miss. "Milder cases of the flu, we've seen all sorts of athletes in different sports make it happen."
How well athletes respond may also depend on whether they've had flu before.
"If you get the true flu, you feel like you've been hit by a truck, so you're not likely to get up and exercise," said Jaffe.
"[An athlete] might have been exposed to the flu previously, and therefore had some antibodies. He may have had a milder case and been able to rise above it," she said.
Athletes who sit out the game may decide they won't be in top form.
"I think a fan's sympathy, at least from me, as both a fan and physician [is that] if someone's got the flu and they don't want to play, they're doing it because they don't want to hurt the team," said Nelson.
That may be something to keep in mind the next time you don't feel you can make it in to help your own team at the office.
But in the meantime, here are some athletes who came down with the flu -- and how that affected their job performance.
Michael Jordan: 1998 NBA Finals
Michael Jordan and the Chicago Bulls won the title six times in eight years from 1991 to 1998, missing out only in the two seasons Jordan missed because of his brief retirement to play baseball.
No one was able to stop them -- apparently not even the flu.
With the Bulls leading the Utah Jazz three games to one in 1998, Jordan came down with the flu. But it wasn't enough to keep him off the court.
In the last two games of the series, Jordan played despite his illness.
He was able to score 45 points in Game 5, but Utah pulled out a narrow 83-81 victory.
But in Game 6, Jordan scored 38 points, finishing the game with a memorable shot to beat the buzzer and lift the Bulls to the crown.
Joe Montana: 1990-91 NFC Championship Game
The San Francisco 49ers won Super Bowl titles in 1988 and 1989 and were aiming for a three-peat in 1990.
The 49ers and the New York Giants started off their respective seasons with 10 straight wins, but each lost their next game, marring what would have been a match-up of the two teams with the best records in NFL history.
The 49ers pulled out a 7-3 win, so the teams seemed evenly matched when they met again for the right to represent the NFC in Super Bowl XXV.
But on Friday before the game, 49ers All-Pro quarterback Joe Montana missed practice with the flu.
Montana felt up to playing by game time, but his presence couldn't lift his team past the Giants. Despite having the league's best record, the 49ers were unable to pull away, and Montana was knocked out of the game in the fourth quarter. The Giants prevailed, 15-13, with a field goal on the game's last play.
New York went on to defeat the Buffalo Bills in the closest Super Bowl ever played, 20-19.
Bruce Smith: 1995-96 NFL Division Playoffs
The Buffalo Bills were the class of the AFC in the early 1990s, advancing to four straight Super Bowls from 1990 to '93.
While they missed the playoffs in 1994, they won their division in 1995 and beat the rival Miami Dolphins in the playoffs' opening round, 37-22.
But days before their next game, against the Pittsburgh Steelers, defensive end Bruce Smith, who had made the Pro Bowl eight times up to that point and was arguably the Bills' best defender, caught the flu, keeping him out of the game.
Pittsburgh scored more points against Buffalo than anyone had all season, winning 40-21.
The Steelers advanced to Super Bowl XXX, where they were beaten by the Dallas Cowboys, 27-17.
The Bills have not won their division or a playoff game since.
Rodney Harrison: 2006-07 AFC Championship Game
The rivalry between the New England Patriots and the Indianapolis Colts became what was arguably the premier rivalry in the NFL so far this decade.
After Tom Brady took over at quarterback for the Patriots, they reeled off six victories in a row over the Colts between the 2001 and 2004 seasons.
But Indianapolis had won the last two games between the teams, leading up to a showdown for the AFC Championship after the 2006 season.
Rodney Harrison, the hard-hitting safety for the Patriots, came down with the flu a few days before the teams faced off. Harrison was not able to play.
The Patriots jumped out to a big lead early in the game and led 21-3 at one point before the Colts began scoring and pulled even.
Ultimately, the Patriots' defense wasn't able to stop the Colts, who emerged with a 38-34 victory.
The Colts went on to beat the Chicago Bears, 29-17, to win their first Super Bowl since 1970, when the team still played in Baltimore.
AFC Championship Game, 2007-08
While the flu may have derailed their championship hopes the year before, the Patriots were able to overcome it in 2007.
Although the Patriots are notoriously guarded about how much the public knows about their players' ailments, quarterback Tom Brady was apparently suffering some symptoms when he led the Patriots over the San Diego Chargers to win the AFC Championship, 21-12.
Chargers linebacker Shawne Merriman was also apparently suffering from the flu in the loss.
In the week leading up to the Super Bowl, several members of the New York Giants, among them starting cornerback Aaron Ross, suffered some of the symptoms.
But it seemed everyone had recovered in time for Super Bowl XLII, a memorable game in which the Giants emerged victorious, 17-14.
Magic Johnson: 1988 NBA Finals
Michael Jordan may be the most famous example of a flu sufferer to help lead his team to the title, but he wasn't the first.
After the Lakers captured the NBA championship in 1987, Lakers coach Pat Riley promised the fans of Los Angeles that he would deliver it to them again the next year.
But fulfilling that wouldn't be easy. The Lakers finished the season with the best record in the NBA, but it took them the full seven games to beat the Utah Jazz and the Dallas Mavericks in the playoffs.
The Lakers met the Pistons in the Finals, only to lose Game 1, followed by their star point guard, Magic Johnson, coming down with the flu.
But Johnson was able to play, delivering 23 points and 11 assists in Game 2, which the Lakers won 108-96, and came up with 18 points, 14 assists in Game 3 to help the Lakers triumph, 99-86.
The series remained tight, but the Lakers ultimately beat the Pistons, 4-3, to deliver on Pat Riley's promise and win their second consecutive title.
Elvis Stojko: 1998 Nagano Olympics
A number of athletes caught the flu bug during the winter games, a problem no doubt exacerbated because of the close living conditions in the athlete's village.
A number of athletes were forced to withdraw or finished well below expectations, including German figure skater Tanja Szewczenko, Canadian figure skaters Marie-Claude Savard-Gagnon and Luc Bradet, and Norwegian speedskater Aadne Sondral.
But perhaps the most prominent athlete to catch the flu was Canadian figure skater Elvis Stojko.
Having won the silver medal in Men's Singles at the 1994 Olympics in Lillehammer, Norway, Stojko was among the favorites to take the gold at Nagano.
Stojko had a minor groin pull beforehand, which he said was exacerbated by the flu, both of which worked against him.
While he was able to capture the silver medal again, he blames the illness for keeping him from gold.
Chris Weinke: 2000 Florida vs. Florida State
Chris Weinke brought Florida State to three straight national championship games as their starting quarterback from 1998 to 2000.
The Seminoles won the 1999 Sugar Bowl, emerging as the national championships.
But their bid to repeat appeared to suffer a setback as Weinke came down with the flu just before their 2000 season-ending game against their archrival, the Florida Gators.
They needn't have worried, as Weinke threw three touchdown passes and Florida State annihilated Florida 30-7 to advance to the Orange Bowl, where the championship would be decided.
Despite Weinke's heroics, Florida State was not able to repeat as national champions, falling to Oklahoma 13-2 in the Orange Bowl.
Weinke was awarded the Heisman Trophy, given to college football's best player, at the end of the season.
1918-19 Stanley Cup
The influenza outbreak of 1918-19 killed 50 million people--more than three times the number killed in World War I.
Many sporting events were able to continue that year--the Boston Red Sox beat the Chicago Cubs 4-2 in 1918 to win their last World Series for a long time--but others ended up bowing out due to the tragic international epidemic.
The Stanley Cup final in March of 1919 pitted the Seattle Metropolitans against the Montreal Canadiens.
The teams played five games in a best of five, but with one game ending in a tie, the series was knotted at two wins apiece headed into the decisive game.
However, a number of Canadiens players had caught the flu at that point. While they attempted to forfeit the series, the Metropolitans did not accept, and so the series was called off.
Joe Hall, a defenseman for the Canadians, died from pneumonia--a complication from the flu--just a few days after the series was cancelled.
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