A new clue into the rate of community transmission of coronavirus may have been uncovered entirely by coincidence.

An outbreak erupted aboard the US Navy aircraft carrier Theodore Roosevelt earlier in April with about 600 crew testing positive.

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Sweeping testing of the entire crew yielded startling results.

Of the 4,800 people on board, one in every eight was infectious.

Of those, 60 per cent had no symptoms.

The expert advice, particularly in the US, predicts a maximum of 50 per cent of people with the virus show no symptoms.

A USS Theodore Roosevelt sailor, who had been admitted to an ICU care unit in Guam, has died. Credit: AP

Asymptomatic carriers of the virus have caused particular headaches throughout Australia.

About 8.3 per cent of confirmed cases across the country have no discernible source, making it likely they were contracted through people without symptoms.

Extending contact tracing was one of the three criteria for coronavirus restrictions being lifted, Scott Morrison announced on Thursday.

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The other two - a stronger testing regime and a strong response capability at a local level - are also primed at preventing community transmission.

Australian health experts and politicians have frequently boasted about the country’s testing capabilities - which are about to be ramped up even further.