Drosten's study was criticized for its static deficiencies.
This criticism was used to revise the study. One of the criticizing statisticians was even taken on to support Drosten's team. The study has neither been refuted nor withdrawn.
Especially since studies from China show that school closures had a great effect on the spread of the virus.
To plead for an unrestricted opening of the schools on the basis of these data is rather daring.