This was an “opinion piece”, not an actual study.
Notice of the withdrawal: https://pubmed.ncbi.nlm.nih.gov/32668870/
Criticism of the opinion piece:
Worst paper of 2020? 5G and Coronavirus induction
https://scienceintegritydigest.com/2020/07/23/worst-paper-of-2020-5g-and-coronavirus-induction/