COVID-19 is not going anywhere, and the PGA Tour has experienced that reality over the last week. Brooks Koepka and Webb Simpson, respectively the No. 4 and No. 5 players in the world, are among five golfers who have withdrawn from the 2020 Travelers Championship. Koepka and Simpson did so out of caution due to contact with someone who tested positive for the coronavirus.

Koepka withdrew after his caddie, Ricky Elliott, registered a positive test, while Simpson made his decision after a family member tested positive. Their personal tests both came back negative Wednesday. Koepka's brother Chase, who earned a spot in the Travelers Championship on Monday after advancing through a qualifying event playoff, also withdrew out of caution. 

Earlier this week, Cameron Champ announced his withdrawal after a positive coronavirus test. He is the only golfer to test positive for COVID-19 this week ahead of the Travelers Championship. Graeme McDowell also bowed out of the Travelers after learning his caddie, Ken Comboy, tested positive. 

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Elliott reportedly spent time with McDowell and Comboy recently, and both Koepka brothers played a practice round with McDowell earlier this week.

"I haven't tested positive for COVID-19, but as I've said all along, I'm taking this very seriously. I don't want to do anything that might jeopardize the health of any player in the field or his ability to compete," Koepka said in a statement. "The right thing to do right now is get home, support Ricky and feel confident that I'm doing what I can do protecting my fellow Tour members, my PGA Tour friends and everyone associated with the Travelers Championship this week."

Simpson shared a similar sentiment. "In the last 24 hours, I had a family member test positive for COVID-19. While my tests this week were negative, I feel like it is my responsibility to take care of my family and protect my peers in the field by withdrawing from the Travelers Championship," he said. "I am going to return home to Charlotte and quarantine under CDC guidelines, and I look forward to returning to competition after that time period."

PGA Tour commissioner Jay Monahan held a press conference Wednesday to announce the positive tests and promise "serious repercussions" and consequences for any golfers who break the protocols in place for tournament events. He also said testing will be beefed up next week at the Rocket Mortgage Classic.

It's not difficult to connect the dots here and see how easy it is for COVID-19 to infiltrate and then spread within the PGA Tour or any sport. When players, caddies and essential personnel are traveling from city to city -- sometimes together but sometimes separately -- it can become a petri dish for the virus to manifest itself.

The PGA Tour will continue to fight to isolate the incidents, but after none the first week at the Charles Schwab Challenge, one last week at the RBC Heritage and now five withdrawals connected to the coronavirus this week before the Travelers Championship has even started, the trend line does not engender confidence about what the future holds.

Simpson won last week's RBC Heritage, and Koepka had his first top-10 finish since the 2019 Tour Championship at the event.