"... incidence started growing exponentially in October 2021 with about 41% of recorded new cases aged twelve or above being symptomatic breakthrough infections, presumably also contributing to the dynamics. At the time, it (i) remains elusive how significant this contribution is and (ii) whether targeted non-pharmaceutical interventions (NPIs) may stop the amplification of the ongoing crisis."

So despite just over half of adults being vaccinated, and just under half of new cases (in adults) being vaccinated "breakthrough" cases, they estimate that it's the unvaccinated spreading covid? Makes no sense unless they're blaming the kids and lumping in with the unvaccinated.