Commercial Fixed Wing
Air Traffic Control Fully Certified
Air Traffic Control Time Certified In Pos 1 (yrs) 5
Confusion; Distraction
ATC Issue All Types; Deviation - Altitude Overshoot; Deviation / Discrepancy - Procedural Clearance
Air Traffic Control Provided Assistance
Human Factors
I cleared Aircraft X to cross ZZZZZ at FL340. I handed the aircraft off to adjacent center and subsequently noticed the aircraft descending through FL340. I called the other center to notify them of the unassigned descent; and the Controller investigated to learn the aircraft was going to FL240.With COVID-19 lack of traffic and talking to a Supervisor about unrelated things; my focus was not 100%. I don't know if the aircraft read it back wrong to me or not. We've always got to be on guard.
Center Controller reported being distracted due to COVID-19 issues and did not hear a wrong read back from a crew; which resulted in an altitude deviation.