Sir Patrick Vallance answers question from media at Downing Street coronavirus press conference

The transcript discusses the effectiveness of the test, trace, and isolation system, emphasizing that it is more effective when case numbers are low. It highlights the need for improvements in the testing system, particularly in speeding up the process to complete it within 48 hours. The speaker acknowledges room for improvement and notes that the system's effectiveness diminishes as case numbers rise.

What is the relationship between the number of contacts and the effectiveness of test and trace?

How quickly should the contact isolation process ideally be completed?