It is well-known that many standards exist and are not used in every service, which causes integration issues.
Table 4 presents smart city projects of several different countries. It the threats concern COVID only, it does not really make sense, as many of the mentioned services simply do not have this goal (e.g. smart grid). If it goes beyond COVID, this is a claim that needs to be backed with a sound and transparent evaluation by the authors or literature. The authors than write that hese services have a limitation in that cannot predict and prevent transmission of threats such as COVID.