New Jersey rocker Jon Bon Jovi and Canadian singer Bryan Adams canceled separate appearances on Saturday night after testing positive for COVID-19. They join a number of artists who have contracted the virus despite vaccination. Jon is fully vaccinated and feeling fine," wrote Bon Jovi's publicist. The musician was scheduled to perform at a three-night "Halloween weekend getaway." Concertgoers, who were asked to provide proof of vaccination or a negative test result, had already filed into the venue when the announcement was made. Adams was slated to perform a Tina Turner tribute at Saturday night's Rock and Roll Hall of Fame induction but canceled his appearance after contracting COVID-19. COVID-19 vaccines, including those manufactured by Pfizer-BioNTech, Moderna and Johnson & Johnson, have waned in efficacy over time, and as more breakthrough cases occur, the music industry is experimenting with solutions to keep up the momentum and maintain the safety of artists and workers on tour. System of a Down were scheduled to perform Oct. 22 and 23 with Korn, Helmet and Russian Circles at Banc of California Stadium until frontman Serj Tankian announced he had contracted a breakthrough case. The shows were postponed to Feb. 4 and 5. English hitmaker Ed Sheeran was scheduled to perform Nov. 6 on "Saturday Night Live" " but the singer announced on Instagram last week that he will do only virtual performances and interviews after testing positive for COVID-19.