  Several recent studies have tackled the issue of optimal network immunization
by providing efficient criteria to identify key nodes to be removed in order to
break apart a network, thus preventing the occurrence of extensive epidemic
outbreaks. Yet, although the efficiency of those criteria has been demonstrated
also in empirical networks, preventive immunization is rarely applied to
real-world scenarios, where the usual approach is the a posteriori attempt to
contain epidemic outbreaks using quarantine measures. Here we compare the
efficiency of prevention with that of quarantine in terms of the tradeoff
between the number of removed and saved nodes on both synthetic and empirical
topologies. We show how, consistent with common sense, but contrary to common
practice, in many cases preventing is better than curing: depending on network
structure, rescuing an infected network by quarantine could become inefficient
soon after the first infection.
