By comparison, in some years the influenza vaccine is under 40% effective. 0.9 deaths per 1 million is amazing (especially given the likely age profile).
See https://www.webmd.com/lung/news/20200902/how-effective-is-th... for some information about the flu vaccine.
In April the vaccination rate was much lower. In a hypothetical situation where 100% of people are vaccinated, all Covid deaths will be vaccinated people.
With so small numbers if vaccinated people dying we should expect that deaths per million to jump around depending on regional outbreaks for a while.