According to media outlet reports on February 22, Jo Kwon has tested positive for COVID-19. 

Reports on February 11 stated that Jo Kwon recently experienced minor symptoms and underwent a PCR Test, and his results have returned positive. Consequently, 2AM's solo concert '22 S/S', originally scheduled to take place from February 12-13 at the Bluesquare Mastercard Hall in Seoul, has been postponed until further notice.

The concert was set to take place both in-person and online, and marked 2AM's first solo concert as a group in 9 years. 

[UPDATE] Jo Kwon's management agency Cube Entertainment has officially confirmed that the singer has tested positive for COVID-19 as of February 11. At time of testing, the singer had completed his 3rd booster dose of the COVID-19 vaccine.