(Bloomberg) -- A dozen members of the Venezuelan delegation at Brazil’s Copa America tested positive for Covid-19, putting a cloud over the opening game for Latin America’s most important soccer tournament on Sunday.

Those infected included both players and staff, who will remain isolated and monitored by a team from the championship’s organizer, Conmebol, as well as Brazilian health authorities, the host country’s Federal District Health Secretariat said in a statement. The Venezuelan team is scheduled to play at the opening game.

On Friday night, Conmebol modified its rules to allow the teams to make as many changes as they need in their player selection as long as they are Covid-related.

The organizer hasn’t commented on the situation with the Venezuelan team, which arrived in Brazil on Thursday. Team members were earlier vaccinated with China’s Sinovac. Venezuela’s Soccer Federation didn’t respond to requests for comments on the possibility of sending a backup team to Brazil.

The infections rekindled health safety concerns that have mired the tournament since the day it was announced. The unrest in Colombia initially forced the tournament to switch venues, and just two weeks ago, it was moved again from Argentina with the worsening spread of coronavirus in the country.

Brazil’s President Jair Bolsonaro, whose administration has been questioned for its virus policies, welcomed the cup to his country, despite having the second-highest number of Covid-related deaths in the world.

Bolsonaro was fined for not wearing a mask after leading a throng of motorcyclist supporters through the streets of Sao Paulo on Saturday, the Associated Press reported.

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