I had never heard about gene drive before.

It refers to making sure all children (and grandchildren etc) inherit a trait, even though the trait isn't necessarily evolutionary beneficial for the organism. The way this is implemented in this case by having a gene that codes for proteins that insert the gene in chromosomes that do not already have it.

This means that by just releasing a few specimen with the gene drive, the entire population can be gene modified in not-that-many generations. A year may be sufficient for insects, since their generations are so short.