From the organisers:

We will start running at 9:00 as usual. Masks must be worn at the starting and finish lines

Mask can be removed during the run but runners must maintain a 2 metre space between each other.

For this reason at the start we will ask the faster runners to take their position at the front flags with slower runners positioning themselves at the back to minimise crowded over taking at the start.

At the end of the run we will operate as usual with position tickets and BIB number entry into the app.

We take this current situation very seriously and would not like to put any of our runners at risk of infection. It is for this reason we ask you to follow our directions so that Sziget Run can continue responsibly.

More: 
Organiser's Facebook page