Health officials don't know whether 48 returnees who stayed alongside four confirmed Covid-19 cases at the Pullman Hotel have been tested.
The 353 people who went through managed isolation at the Auckland facility between January 9 and 13 were ordered to isolate and get tested on Sunday afternoon after news broke of the Northland woman testing positive.
As of midday today 305 of those guests returned negative tests but 48 tests are still outstanding.
A Health Ministry spokesperson said those people were re-contacted this morning but did not know whether those people were awaiting results or if they'd been tested at all.
Hipkins said he understood the contact tracers had been "very effective" in getting in touch with the Pullman guests - the delay was in those people getting their tests but he couldn't detail what those delays were.
And he was "sure" the guests who'd been contacted and told to isolate were doing so.
Director general of health Dr Ashley Bloomfield said it might be that the majority of the 48 outstanding returnees had been tested and officials were awaiting results.
Everyone who is followed up with has a special code on their test sample so the laboratory knows to expedite the processing, he said.
Epidemiologist Michael Baker from Otago University's department of public health said it was hard to assess the level of risk those outstanding tests posed to the public.
"A bit of time has elapsed and you know that we know unfortunately that the virus can spread for several generations in the community undetected. So that means it will be obviously more assuring that all of those people have been tested at this stage."