False negative stalled isolation order

DOZENS of people exposed to the UK coronavirus strain at a Coburg family gathering were allowed to circulate in the community after it took investigators a week to confirm a “weak positive” test result.

As details of the latest cases raised concerns of a gap in the containment ring around the Holiday Inn outbreak, Health Minister Martin Foley said it was too soon to know if Victoria’s five-day lockdown would be extended.

The Queen Victoria Market and two tram routes were late Sunday added to the list of exposure sites.

Victoria — which has stopped taking international passengers — also triggered a political storm after refusing to say if it will take the same number of arrivals it used to when lockdown ends.

After the first case having been confirmed on February 7, the Holiday Inn outbreak on Sunday rose to 16 cases when the first nonhousehold contacts were confirmed to have COVID-19. Investigations have now concluded the latest cases — a three-year-old child and a woman — caught the highly infectious B117 variant while it was circulating at a private gathering in Sydney Rd, Coburg on February 6.

Despite first examining the gathering a week ago when it was revealed a COVID-19 Quarantine Victoria worker had attended, contact tracers ruled it out as an exposure site when the woman tested negative on February 7 — meaning most of the 38 guests did not have to isolate.

It was only when another male attendee later tested positive investigators re-examined the woman’s negative test in more detail and found it was actually a “weak positive”.

Victoria’s Chief Health Officer Brett Sutton defended the week it took to identify the Coburg risk, saying there had been no reason to isolate guests based on the woman’s initial negative test.

Prof Sutton said false-positives and false negative COVID-19 test results were extremely rare.