As Covid-19 cases start to rise again, computational biologist David Welch wants to see mask restrictions tighten.
Winter is coming and New Zealand will remain at the Orange setting to keep the Omicron outbreak under control.
"While daily cases numbers have flattened nationally, they are again beginning to increase in the Northern region and hospitalisation rates have also increased slightly over the past month," Covid-19 Response Minister Chris Hipkins said.
There is likely to be a second wave, Hipkins said.
University of Auckland computational biologist David Welch says with Covid cases slowly rising, its good to stay in the orange setting.
"I think it's very sensible to stay at orange at this point. Orange isn't particularly restrictive but it does help with masking and it sets clear rules around isolation and stuff.
"It does look like cases are starting to rise slowly in many parts of the country. We saw a very big peak and we came down from that but we didn't come down super low."
Welch said waning immunity, a new season and new variants are all factors in driving numbers up.
Public health measures make sense to try to take the pressure off a little, he said.
"Winter does make things worse, like a lot of other respiratory viruses Covid does spread more easily in the colder months.
"And of course there are the other respiratory viruses around that hospitals and doctors are having to deal with."
Welch would like to see stricter rules around masking in some places.
"I'd say masking is very effective so it's good that it's encouraged in some places, I think it could be more strongly encouraged in other places, for example we're seeing cases rising in schools at the moment, vaccination rates among children are very low so they're a vulnerable group.
"I'd like to see masks mandated in schools and I'd like to see more being done on ventilation to be understand risky indoor environments."
CO2 monitors are very cheap and effective, giving a good indication of indoor risk, he said.
Welch hopes the 4th vaccine rollout will begin at the start of June rather than later in the month.
"There's well over a million people who are due for a dose now but haven't taken that opportunity so I'd strongly encourage anyone out there to get a vaccination if they're due."