Fig. 1.

The rationale of the paper. The spreading of the SARS-CoV-2 may be modeled using a network whose nodes are people while edges are the contacts among them. The spreading may be summarized in an SIR model using two main parameters $\beta$, and $\delta$, representing the rate of novel infected people and the recovery rate. The network may be represented using the adjacency matrix of the resulting graph. Spreading may be contained when the following condition holds $\frac{\beta }{\delta }$$⩽$$\frac{1}{\lambda }$, where $\lambda$ is the largest eigenvalue of the adjacency matrix. We hypothesize that an individual’s vaccination is equivalent to deleting a node (or equivalently to deleting the edge of the contacts).