Before revision:  Our analysis reveals that for COVID-19 close contact parameters, the storage space requires maintaining the contact graph of ten million users  having 14 days  close contact data in  PHA server takes 55 Gigabytes of memory and preparation of the contact list for a given set of the infected person depends on the size of the infected list  .
After revision:  Our analysis reveals that for COVID-19 close contact parameters, the storage space requires maintaining the contact graph of ten million users having 14 days close contact data in PHA server takes 55 Gigabytes of memory and preparation of the contact list for a given set of the infected person depends on the size of the infected list . Our centralized digital contact tracing framework can also be applicable for other relevant diseases parameterized by an incubation period and proximity duration of contacts .