Next month's Indianapolis 500 is set to be the most-attended sporting event since the start of the Covid-19 outbreak as 135,000 fans will be allowed inside the sprawling Indianapolis Motor Speedway (IMS), organisers said.
A plan developed along with state and local health officials determined the IMS could be filled to 40 per cent capacity for the May 30 race.
"The number one thing fans can do to ensure a great race day is get vaccinated as quickly as possible," Mark Miles, chief executive of the company that runs IndyCar and the IMS, said in a news release.
"We continue to offer vaccinations at IMS and will be extending our mass vaccination clinic throughout the month of May. This is all part of the effort to continue getting Indiana back on track."
The Indianapolis 500, which last year was held without fans due to growing concerns around coronavirus, is the crown jewel of American open-wheel racing and one of the world's biggest single-day sporting events.
The safety plan for the race includes mandatory masks throughout the venue and temperature screenings upon entry.
Among other safety measures in place will be spacing between customer groups, frequent cleaning, no race day general admission tickets sold and readily available hand sanitising stations.
The IMS will also offer vaccination days from April 24-30 and on select days from May 1-27.
The Indianapolis 500, which is traditionally staged each US Memorial Day weekend, was postponed last year until August due to Covid-19 and was won by Japan's Takuma Sato.