Football fans with tickets for the European Championships this summer could be given a refund and then forced to reapply.
With stadium capacities set to be limited due to the pandemic, UEFA is exploring how best to reallocate the limited number of seats.
This follows a meeting of the host countries on Wednesday at which UEFA reaffirmed its commitment to staging the tournament across 12 cities.
Another option would be to do redistribute tickets via a ballot but that is considered logistically tougher.
More than one-and-a-half million of the three million tickets for the tournament had already been sold, though many will have been returned to UEFA before this week's deadline.
To limit international travel, it is also possible that only home fans will be able to attend group games. Many of the national representatives are pushing UEFA to take steps to prevent international travel by supporters because of the pandemic.
The decision on stadium capacities will need to be made by individual governments. UEFA has set a deadline of early April for host nations to submit their plans for fans inside stadiums.
The tournament is scheduled to begin on June 11, with the final at Wembley on July 11.