Tournament organisers had hoped to allow fans, but the US PGA Championship will take place without spectators.
After finishing seventh at the RBC Heritage, Brooks Koepka was hopeful about his form and fitness for the rest of 2020.
The RBC Heritage is unlikely to see Rory McIlroy on a regular basis as the world number one thinks other events suit him better.
American Webb Simpson continued his good form this year, winning the RBC Heritage.
World number one Rory McIlroy discussed Nick Watney's positive COVID-19 test following Saturday's third round.
Brooks Koepka is one of 17 players sitting within three shots of Webb Simpson, Tyrrell Hatton, Abraham Ancer and Ryan Palmer.
Nick Watney's close contacts have tested negative for coronavirus, as Justin Thomas described Hilton Head Island as "an absolute zoo".
After Nick Watney tested positive for COVID-19, Rory McIlroy and Brooks Koepka said they were near the American beforehand.
Webb Simpson carded a second straight 65 to grab a one-stroke lead at the RBC Heritage.
Back at the RBC Heritage for the first time since 2009, Rory McIlroy struggled to get comfortable.