The question of whether using data gathered through the National Health Insurance (NHI) program intrudes on personal data privacy is an ethical and legal issue, but any decision about whether to allow the use of such data should be based on whether any such infringement has ever happened, rather than on the suspicion that it might happen in the future.
I might have been using this kind of data for longer than anyone else in Taiwan. In 1980, when I was in the US doing further studies in the field of environmental epidemiology, I gained my first experience of big data