The winter COVID-19 surge is here, with Tuesday's daily case numbers up more than 3000 on the previous day.
Tuesday's seven-day rolling average is up almost 1800 on last week and a new Omicron subvariant, BA.2.75, has arrived from India, the Ministry of Health said. In addition, the BA.5 variant was set to become the dominant strain in New Zealand.
Immunologist Dianne Sika-Paotonu said there were early signs the BA.5 strain was successfully evading immunity.
Scientists in South Africa, where Omicron was first detected, found earlier this year that BA.4 and BA.5 could dodge antibodies from earlier infection but were far less able to thrive in the blood of people vaccinated against COVID-19.
"BA.5, in particular, has been generating a lot of attention recently but for all the wrong reasons," Dr Sika-Paotonu said. "What we can see now is BA.5 is found in lots of different countries and is causing surges in COVID-19 cases.
"Another subvariant, the BA.4 subvariant… and BA.5 share some of the same identical mutations in the spike protein which affects the way in which the virus interacts with our host's cells, but also with the potential to evade our host's immune response."
Dr Sika-Paotonu AM that Omicron was continuing to spread fast and hospitals were under pressure.
"All those studies are suggesting that these successive COVID-19 waves might be considered milder for some - this is certainly not the case for everyone," she told host Melissa Chan-Green.
"We really do need to keep an eye on what's going on here because, as we can see here in Aotearoa New Zealand, the higher transmissibility of the subsequent variants of the SARS-CoV-2 virus has meant that we're still getting very high COVID-19 case numbers - which means more people becoming unwell and this is all happening at a time when winter illnesses are kicking in."
She expected new subvariants to continue emerging while global vaccine inequities remained.
"Right now, as they emerge, there is time that's needed to try and understand more about how these subvariants behave, and what their impact will be on our populations," she said.
"The jury's still out on the BA.5 subvariant that we've been discussing. Although it's been shown to be more highly transmissible and able to evade our host's immune responses, we still don't know whether it causes more severe illness, more hospitlisation and therefore more death."
Dr Sika-Paotonu said while New Zealand had high COVID-19 vaccination levels, people still needed to be vigilant.
"We can all do very simple things to help keep ourselves safe and protected, and none of this is new - just because we are tired of the virus doesn't mean that the virus is going anywhere in a hurry.
"Living with the virus still means being responsible and so what this means is ensuring that we're vaccinated, that we're boosted, that we get tested and report those test results, that if we're unwell we stay at home, we isolate."
