Not comfortable about travelling during the coronavirus pandemic, Barty is the biggest name yet to opt out of the August 31 to September 13 major because of the global heath crisis.

"My team and I have decided that we won't be travelling to the US and Western and Southern Open and the US Open this year," Barty said in a statement to AAP on Thursday.

"I love both events so it was a difficult decision but there are still significant risks involved due to COVID-19 and I don't feel comfortable putting my team and I in that position.

"I wish the USTA all the best for the tournaments and I look forward to being back in the US next year."

Barty is still weighing up whether or not to resume her season in Europe and ultimately try to defend her French Open crown in Paris.

The claycourt major was rescheduled from May-June to a September 27 start.

"I will make my decision on the French Open and the surrounding WTA European tournaments in the coming weeks," Barty said.

Barty has been closely monitoring the coronavirus situation at home in Queensland for months.

The 24-year-old was among a raft of big names to express concerns about the US Open going ahead as planned in the same annual timeslot despite Flushing Meadows at one stage being used as an emergency hospital for the outbreak.

Men's world No.1 Novak Djokovic and defending US Open champion Rafael Nadal were also doubtful starters but both have since entered the Southern and Western Open, which has been moved from Cincinnati to New York where USTA officials will create a biosecurity hub for three weeks.

But women's world No.2 Simona Halep, 2018 winner Naomi Osaka and defending champion Bianca Andreescu have not entered the Southern and Western Open, which starts on August 15.

Such is Barty's huge points lead over Halep and world No.3 Karolina Pliskova that the Australian is assured of carrying the top ranking into the rescheduled claycourt swing - regardless if she decides to play or not.

The Australian Open semi-finalist has already held the top ranking for a total of 35 weeks - the 12th longest reign in history - and longer even than all-time greats including Venus Williams, Maria Sharapova and Kim Clijsters.

Australian Associated Press