Some people with clear Covid-19 symptoms are consistently negative on rapid antigen tests (RATs), sparking concern that all infections aren't being picked up.
That was the case for Will Page.
"There were six in our house, five who had Covid-19 and I just assumed I would have caught it," he told 1News.
"We then got our RATs, and I kept doing them - negative, negative, negative."
Siouxsie Wiles has a “hack” that might help. (Source: 1News)
It was a similar story for Alice Cranfield's daughter.
"She's lying on the floor, ice pack, she couldn't get her temperature down - but she kept getting negative test after negative test," she said.
"We were scratching our heads a bit."
Lily's flat in Auckland also went into isolation - all with symptoms, however not everyone initially tested positive.
Seven Sharp provided the answer to the question plaguing many close household contacts in the current Omicron outbreak. (Source: Seven Sharp)
"Probably five or six times I tested negative on RATs before I tested positive," she said.
"That was what really terrified everybody in the house was that even on my flatmates worse days of symptoms they tested negative - so that was really concerning."
Microbiologist, Siouxsie Wiles, said there were lots of reasons this could be.
"One reason is that maybe they don't have Covid-19, we are interacting a lot and perhaps there are lots of cold viruses out there," she told 1News.
"But we do know there is lots of Covid-19 out there.
"One potential reason is that they could be testing too early, we know that if somebody is vaccinated they are going to mount an immune response and that's going give rise to those symptoms really quickly, so they might need to wait a day of two to get enough virus there for the test to detect.
"Another reason is that people might not be swabbing themselves properly - it's very tricky, the nose doesn't look like what we think it looks like inside and some of the instructions are a little bit ambiguous about where you should swab."
She encouraged people to insert the nasal swab in the RAT "low and slow" in the nostril but noted that according to some studies the nose wasn't the best place to test for Omicron.
"With Delta they found that the nasal swab was more reliable than the throat swabs, but with Omicron, they found they missed probably one in ten cases just using the nasal swab rather than the saliva swab."
She said there were ways to "hack" the RAT to get more accurate results, although added people needed to be extremely careful.
"One of the things you can do - be careful - is swab the back of the mouth before you use the same swab to do your nose as well," she said.
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