Brooks Koepka is one of five players to withdraw from the Travelers Championship, although the tournament will continue despite three positive coronavirus tests.
PGA Tour commissioner Jay Monahan updated the media on Wednesday after Cameron Champ, Graeme McDowell's caddie Ken Comboy and Koepka's caddie Ricky Elliott returned positive tests for COVID-19.
The Tour returned at the Charles Schwab Challenge earlier in June, but Nick Watney became the first confirmed case since the restart at the RBC Heritage last week.
Monahan confirmed the news of the latest positive tests and a series of withdrawals, yet the Travelers will go ahead as planned.
Champ, McDowell and Koepka were joined by Webb Simpson and Chase Koepka - Brooks' brother - in withdrawing.
"We have been working since March to develop a comprehensive health and safety plan that would be considered a best practice among professional sports leagues," Monahan said.
"While we've been thorough in building an implementing a programme that mitigates as much risk as possible, we knew it would be impossible to eliminate all risk, as evidenced by the three positive tests this week.
"We need to use these developments as a stark reminder for everyone involved as we continue to learn from an operational standpoint."
Four-time major champion Brooks Koepka said: "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 jeopardise the health of any player in the field or his ability to compete.
"I was planning to take the next two weeks off anyway, so 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."
Commissioner Monahan added: "Rest assured that the PGA Tour will always do the right thing as it relates to our players, our fans, our constituents and make sure that we create the safest environment possible.
"We are looking forward to reintroducing fans the week of Memorial Tournament, but rest assured we're only going to do it if we think it's a health and safe environment for our players, caddies, our staff and also the fans that would be attending."