Lee Westwood says he will not play at next month's US PGA Championship, despite coronavirus quarantine rules being relaxed for players and caddies.
The lifting of the 14-day quarantine on arrival in the United States means Westwood could have gone straight into the tournament "bubble" and played.
However, he said: "I still don't feel comfortable and I don't feel it is right to jump on a plane for 12 hours."
The first major of 2020 will be played in San Francisco with no fans present.
With the Open Championship having been cancelled, the other three majors in the men's game are all set to be played in the US.
Harding Park will host the US PGA, which was originally scheduled for May, from 6-9 August. The US Open is set to be contested in September, with the Masters being held in November.
Westwood's world ranking of 34 means he automatically qualifies to play in the majors.
But the 47-year-old Englishman, who has won 44 tournaments but never won a major, said: "I'm still more concerned that America doesn't take it as seriously as the rest of the world. It still seems to be one of the hotspots for outbreaks.
"I can control me not getting the virus and take all the measures I can, but somebody might pass it on. I don't really want to get ill with it and I'm slightly asthmatic.
"There are too many what ifs. If you take all them into consideration, there is something wrong."
The number of Covid-19 cases in the US is close to four million and there have been over 145,000 coronavirus-related deaths.
Westwood has been hosting the British Masters at Close House this week, won by Italy's Renato Paratore, as the European Tour begins a run of six successive tournaments in a 'UK swing'.
He is a member at the course near Newcastle and while he paid tribute to the European Tour for putting the event on, he says he has felt "out of my comfort zone" given the Covid-19 protocols in place.
"When we turned up on Monday I was surprised how thorough everything was," said Westwood, who shot an eight-over 79 in the final round to finish on eight over par for the tournament.
"The testing protocol we have all been through has been a success. I don't think anybody has tested positive so hopefully they will carry on next week.
"But in 28 years of playing on Tour this is a shock to the system, isn't it?
"Whenever I come out and play the tournaments now it is almost about seeing my mates and the sociable element of it all, and you're not getting that at the moment.
"I've never seen so many players on the range at 8 o'clock at night trying to avoid their hotel rooms.
"It's just not the life I'm used to. I go out on the golf course and I am struggling for motivation a little bit. There is a lot more to consider."
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