On July 13th, BTOB Minhyuk's vocal teacher was confirmed to have tested positive for COVID-19. Soon after, Minhyuk took a rapid COVID-19 test and tested negative. 

Below is the official statement released by Cube Entertainment, regarding the issue:

"Hello,
This is Cube Entertainment.
On the night of July 13th, BTOB Lee Minhyuk's vocal teacher was confirmed to have tested positive for COVID-19
In response, Minhyuk underwent a rapid COVID-19 test in order to take preemptive measures, and the results showed that he tested negative.
No further action has been instructed by health authorities so far, but in order to prevent the spread of COVID-19, he will self-quarantine in his home for the time being until further instructed by health authorities.
Once again, we apologize for causing concern to many people.
We will continue to follow the quarantine guidelines of the health authorities and do our best to maintain the health and safety of our artists."