  Despite the progress in medical care, combined population-wide interventions
(such as physical distancing, testing and contact tracing) are still crucial to
manage the SARS-CoV-2 pandemic, aggravated by the emergence of new highly
transmissible variants. We combine the compartmental SIDARTHE model, predicting
the course of COVID-19 infections, with a new data-based model that projects
new cases onto casualties and healthcare system costs. Based on the Italian
case study, we outline several scenarios: mass vaccination campaigns with
different paces, different transmission rates due to new variants, and
different enforced countermeasures, including the alternation of opening and
closure phases. Our results demonstrate that non-pharmaceutical interventions
(NPIs) have a higher impact on the epidemic evolution than vaccination, which
advocates for the need to keep containment measures in place throughout the
vaccination campaign. We also show that, if intermittent open-close strategies
are adopted, deaths and healthcare system costs can be drastically reduced,
without any aggravation of socioeconomic losses, as long as one has the
foresight to start with a closing phase rather than an opening one.
