MADISON, Wis. (AP) — The Madison Ballet’s final performances of “The Nutcracker” were canceled Sunday due to several breakthrough COVID-19 cases within the company.

Ballet officials say “incredible efforts” were put forth to ensure the safety of audiences and artists, but the virus outbreak forced the “difficult decision” to call off the final shows.

The company had scheduled afternoon and evening renditions of “The Nutcracker.” Attendees for previous shows were required to wear face masks and show proof of vaccinations or negative COVID-19 tests with a photo ID.

The Madison Ballet earlier this month thrilled audiences of Afghan refugees with four performances of the holiday classic at Fort McCoy in eastern Wisconsin.