Microbiologist Siouxsie Wiles and cellular immunologist Anna Brooks say we still need to be serious about Covid, and now they're most worried about the long-term health of younger people.

Joining Matt McLean on Breakfast today, Wiles and Brooks spoke about how the danger Covid poses is changing.

Although New Zealand is emerging from it's third major wave, the baseline number of infections remains high - 13,880 cases were reported last week, and experts have grave concerns about the country not taking infection seriously.

"Whether you've had it before or not," Brooks said it's absolutely serious. "Every time we get infected we have those risks of long-term impacts, so we always need to be mindful."

"When the pandemic started, what we saw were the really initial impacts of a disease for which we had no vaccine and no treatments," Wiles explained. "We know that is more dangerous for people that are older and people who are immunocompromised."

With vaccines and antivirals, those people are better protected. But just getting Covid "increases your risk of all sorts of things - heart attacks, strokes, you name it, it seems to impact," said Wiles.

"Now, I’m worried about everyone going 'oh it's fine because i'm not likely to die - I'm young'. You are the ones we're really worried about now because your life expectancy is now lower because of all these other long term impacts."

"It’s the younger demographic" Wiles said is most at risk, "the 30s to 50s. That's huge, that's our workforce… there’s no one untouched by this."

Brooks described Long Covid symptoms as a spectrum, with some people "who self-identify and absolutely know life has changed for them".

The neurological symptoms are less obvious and often taken for granted, she said.

"It's very hard to characterise and identify that you have neurological symptoms - you may have memory problems or difficulty communicating."

"We're hearing people might be impacted for six months, a year, two years. We also know there are people that are sometimes getting worse or we're expecting this is a lifetime condition," said Brooks.

Wiles added that some with long Covid meet the diagnostic criteria for chronic fatigue syndrome, and some of these people never recover.

"It just has such an impact physically, mentally, economically... We have tools in our toolkit that we could be using but we simply aren't."

Wiles and Brooks agreed that the best public health measures are invisible ones.

"When you turn on the tap you know your water is safe to drink" because "several hundred years ago a revolution happened in sewage and water treatment," Wiles said.

"That's what we want to happen with air. We know that with ventilation, with air purification - those are the things that make the air safe. Even if someone has Covid - and testing, provisions for people to stay home if they are infected."