Victorian Premier Daniel Andrews (Image: AAP /David Crosling)

How many known close contacts of COVID-19 carriers in Victoria and NSW are notified by government tracing teams?

The answer may seem self-evident -- all of them -- but if the experience of other countries is anything to go by, many close contacts may be falling through the gaps of the tracing system.

In England, a quarter of people referred to National Health Service (NHS) tracers cannot be reached due to a combination of unanswered calls and incorrect contact details. Of referrals who are successfully interviewed, around a third of the close contacts they provide to tracers are also proving impossible to find.