Good morning Stephen,
I was not personally aware of such cases after the restart so I asked the European Chess Union overnight.
An official has answered with the following information:
- There were at least two cases, one in Austria and another in Switzerland.
- Both were reported by players themselves after they went home after tournaments.
- The organizers are not so keen to report.
- Of course, it cannot be proven where people got infected and since their fellow players didn't volunteer any information about post-tournament status, it is unknown whether they infected someone else at the events.
In the same message exchange, it was emphasized that the ECU has medical protocols in place and considers an infection risk "very low" if organizers adhere to them. The ECU discourages tournaments where organizers don't guarantee that such safety protocols are observed.