  Non-pharmacological interventions (NPIs), and in particular social
distancing, in conjunction with the advent of effective vaccines at the end of
2020, aspired for the development of a protective immunity shield against the
spread of SARS-CoV-2. The main question rose is related to the deployment
strategy of the two doses with respect to the imposed NPIs and population age.
In this study, an extended (SEIR) agent-based model on small-world networks was
employed to identify the optimal policies against Covid 19 pandemic, including
social distancing measures and mass vaccination. To achieve this, a new
methodology is proposed to solve the inverse problem of calibrating an agent's
infection rate with respect to vaccination efficacy. The results show that
deploying the first vaccine dose across the whole population is sufficient to
control the epidemic, with respect to deaths, even for low number of social
contacts. Moreover, for the same range of social contacts, we found that there
is an optimum ratio of vaccinating ages > 65 over the younger ones of 4/5.
