No, blood is not stored for 30 days for testinG. Donated blood and vlood products go thru A very RIGORUS testing process, using several different kinds of tests....
The blood supply is totally safe.
so it means blood is stored for atleast 30 days and then cheked reguraly
The screening of blood in blood banks happens mulitple of times before anyone is transfused with donated blood and has been since 1985.