Lung-function appears to be fully recovered in minors:

In one [study], Swedish researchers found that even asthma patients had no significant impairment in lung function.

In the other, German researchers found unimpaired lung function after kids and teens had a COVID-19 infection — unless their infection was severe.

“The COVID-19 pandemic has raised questions about if and how the lung is affected after clearance of the coronavirus infection, especially in young people from the general population with less severe disease. Until now, this has not been known,” said Dr. Ida Mogensen, a post-doctoral fellow at the Karolinska Institute, who led the Swedish study.