Why a doctor thinks influenza might never return as strong as it used to be

The potentially deadly influenza virus might never again have the same hold on New Zealand as it did before the Covid-19 pandemic, a Rotorua doctor says.

Each year, before Covid-19, more than 200,000 Kiwis catch influenza - the flu - and an estimated 500 die from it. That's more than the annual road toll.

However, 2020 was different, with flu rates deep-diving across New Zealand as a direct result of Covid-19 and the lockdown, experts say.

Rotorua general practitioner Dr Cate Mills, from Three Lakes Clinic, suspects the flu will have a limited impact in the future.

"All the precautions that we're taking for Covid-19, equally work for the influenza virus," she told the Rotorua Daily Post.

"The hand hygiene, the social distancing, and not going out when we're sick [means] we're not transmitting it as well. It's great."

Rotorua GP Dr Cate Mills from Three Lakes Clinic. Photo / File

The flu is a virus that spreads quickly from person to person, with symptoms including fever, chills, aches, runny nose, a cough, and upset stomach.

Immunisation is the best defence against the flu, the Ministry of Health says.

People are at greater risk of the flu if they are aged over 65, are pregnant, or have a health condition such as diabetes or heart disease.

The flu virus infects people's noses, throats, and lungs and is normally worse than a cold.

"Proper influenza is an infection that generally is quite debilitating for people - like you wouldn't be able to go to work. It lays you out," Mills said.

"You have a high fever, lots of muscle aches and pains, and just feel really sick. It's like being hit by a bus, is how some people describe it."

Immunisation Advisory Centre director Dr Nikki Turner says the main reason flu rates were so low in 2020 was because lockdown occurred at the start of flu season.

"There was also a high uptake of the flu vaccine and a heightened awareness of the importance of hand washing, social distancing and staying at home when sick," she said.

Mills says Rotorua is "absolutely" still seeing low flu rates in the area, though it's not totally unexpected for this time of year.

"It's early in the year for us to be seeing it anyway but certainly our experience last year is that it was almost non-existent. It was amazing," she said.

"Normally we see quite a bit of it but the rates last year were phenomenally low."

In temperate climates such as New Zealand's, people are more likely to catch the flu in winter but Mills doesn't see that happening.

"Life's not going to be normal again. I think [Covid-19] will change behaviour long term."

Flu rates are also low in Tauranga, Fifth Avenue Family Practice GP Dr Luke Bradford says.

Tauranga GP Dr Luke Bradford from Fifth Avenue Family Practice. Photo / George Novak

He too puts it down to the impact of Covid-19, saying managed isolation and quarantine is helping to keep any international strains out of the country.

"Any strain that is here is the same strain as last year, as opposed to one that has been introduced from the Northern Hemisphere," he said.

Anyone who thinks they might have the flu should call their GP, instead of trying to see them in person, for a phone consultation in the first instance.

Turner says it is unlikely to have much flu coming into New Zealand from overseas with ongoing border controls this year.

She says the flu should never be taken for granted and people need to continue supporting flu vaccination and continuing preventative virus spreading measures.