Djokovic has long admitted he did not want to be vaccinated and told the BBC in February he was willing to sacrifice playing in the biggest tournaments to stick to his principles.
That came a few weeks after he was deported from Australia following a dramatic and high-profile court case about the validity of his visa to enter the country.
Asked why he did not want to be vaccinated, Djokovic said he was trying to be “in tune” with his body as much as he could be.
Djokovic said he had “always been a great student of wellness, wellbeing, health and nutrition” and his decision had been partly influenced by the positive impact factors such as changing his diet and his sleeping patterns had had on his abilities as an athlete.
But he insisted he was “never against vaccination”.
Not being vaccinated did not prevent Djokovic playing at the French Open or Wimbledon and, with most countries which host ATP events having now relaxed rules, the US Open could be one of the last events where this is an issue for the former world number one.