The Auckland border worker Covid-19 case's household contact who initially had a weak positive test result for the virus has now tested negative.
Director-General of Health Dr Ashley Bloomfield confirmed the news on Breakfast.
“The re-testing of the household member who had returned the initial weak positive, the re-testing there and the serology testing were both negative,” he said.
“So, this is a little bit of a puzzle but it suggests it could have been a false positive, it could have been early infection, what we’re going to do is keep that person as a case under investigation and probably do some further testing in the next day or two."
He said there's "no suggestion of any further spread" of the virus following this development.
“Our case remains asymptomatic, she is continuing to do well and this is probably the impact of the vaccine, we find this with many vaccines that even if someone who is vaccinated does get infected, then the illness is much more mild or even asymptomatic.”
Bloomfield also revealed that genome sequencing for the border worker, a cleaner at the Grand Millennium, showed a link to a person with the UK variant who had stayed at the hotel from March 13 to 15.
“We have got genome sequencing back, that has shown that the genome is the one first identified in the UK, the B.1.1.7 variant, It matches a person who was staying at the hotel from the 13th to the 15th of March,” Bloomfield said.
“The important thing about that was actually that was before our new case had their second vaccination, that’s the first useful information we’ve received overnight.”
Bloomfield said regular testing of the border workforce would continue despite the vaccine, as he explained what the jab had been proven to do.
“There are three things that the vaccine does, first it does protect most individuals from being infected in the first place, they will basically fight off the virus if they are exposed to it, without becoming infected,” he said.
“Secondly for people, and I think our case here is a good example, who do get infection that is detectable, it makes the illness more mild so they’re much less likely to become severely unwell, to be hospitalised, or die, very, very effective in reducing serious illness or death.
“The third, there is increasing evidence about reducing onward transmission but this is one of the things that as you point out, actually one of the challenges is that people who are infected because they are asymptomatic, maybe going about their normal work and potentially able to transmit the virus.
"I‘ll say potentially because we are getting that evidence that it does reduce transmission, that’s why we continue to do the regular testing of our border workforce.”