There are now fears of a superspreader event after Kheir was reportedly among those to test positive after lavish celebrations at a Melbourne venue which hosted key figures from the racing world.
It comes after the Victoria Racing Club (VCR) said two people who were at the races had tested positive to coronavirus.
The VCR said on Friday a contractor who worked at the racecourse on Derby Day and Melbourne Cup Day, and a patron who attended the latter, had tested positive.
Both people are fully vaccinated and the two cases are not linked.
"The VRC is working closely with the Department of Health which has been very supportive of the club's Covid-safe event pan and management of the two cases and the conduct of the Covid-safe event of the Melbourne Cup Carnival," the club said in a statement.
"The contractor who tested positive worked two full days in The Arbour in the Purple Zone on the ground floor of the Club Stand.
"The Department of Health has advised the VRC that patrons and staff who attended The Arbour on Cup Day are considered at low risk.
"Based on this, patrons and staff are advised to monitor their health and get tested if they develop any symptoms.
"The patron who tested positive attended the deck bar within the Green Zone on Cup Day and the Department of Health is in direct contact with the patron and their two social close contacts, who are also fully vaccinated.
"Patrons who attended the deck bar on Cup Day are being contacted directly via SMS by the VRC and staff have also been contacted."
About 10,000 people attended the Melbourne Cup.