An expert is warning against complacency in the fight against Covid-19 as the number of hospitalisations spikes.

As a second wave of Omicron takes hold, Auckland University Immunologist Anna Brooks is urging Kiwis to keep up the fight against virus by wearing masks.

She also wants the second booster shot to be made more widely available to help stop the virus' spread.

"We just need to come together as a country and say, 'Let's do this, let's get through winter. Mask up."

The Ministry of Health said yesterday there had been a significant increase in the number of Covid-related hospitalisations this weekend.

"We know there will also be increased demand for primary and community care services as Covid-19 cases increase," the ministry said.

"We know there will also be increased demand for primary and community care services as Covid-19 cases increase."

There were 662 people in hospital with the virus yesterday, with 13 in intensive care.

Hospitalisation numbers have risen by nearly 80 since Friday.

Meanwhile, there were 7461 community cases recorded yesterday and eight deaths. The seven-day rolling average was 8690.

Brooks said this was alarming. We were now at the most precarious point in the pandemic for New Zealand so far.

"I think it's not unexpected that human behaviours are now creeping in, we are all sick of this pandemic, we don't want to be restricted, we want to get back to normal life, but just wanting it to go away is not going to make it go away."

The only way to stop hospitals from being inundated was to maintain the protections we know have worked previously, like masks, Brooks said.

Travelling by plane recently, the pitfalls of our Covid protections had become apparent to her.

Only a few obeyed the compulsory mask-wearing inside the airport, she said. A few more obeyed the compulsory wearing while boarding. However, most took off their mask to enjoy a coffee or food on the plane.

This week, Air New Zealand said customers should expect delays and some cancellations on flights over the school holidays due to staff illnesses.

Brooks said this was unsurprising considering how often these staff were constantly exposed.

"It starts with good guidelines to say, 'Hey this thing's airborne, it's not magical air when you want to have a coffee on a plane', we need to focus on the fact we are still in this wave.

"No one wants to see more harsh restrictions, however people need to understand that these simple actions affect much more than they realise.

"It's affecting our health industry, our travel, our retail, everything."

Currently, a second booster is available for Pakeha over 65, Māori and Pacifica over 50, those in aged care and those working in health care.

The Australian government announced that starting next week, it would become available for those over 30.

Brooks recommends that New Zealand follow suit.

"It makes sense for the second dose of the booster to become available for all those who want it.

"There are plenty of people who don't fall under that 'essential' category that still want to protect themselves, a vulnerable family member or their ability to work.

"Hopefully extending access will come sooner than later, because we do have waning immunity. The best-case scenario is that will have updated vaccines, one that tackles the current and most prominent variants within our communities."

The total number of publicly reported deaths with Covid-19 is now 1671.