Dr. Ashley Bloomfield is stepping down as director general of health. Video / NZ Herald

Scientists have already discovered early cases of flu in New Zealand after a two-year break. What can you expect from the familiar trouble this season? Jamie Morton explains.

The flu is finally back – and it could be a serious season

Now it may seem like a lifetime ago, but in 2019 New Zealand last had flu season.

When Covid-19 appeared early next year, the unprecedented steps we took to block it also led to the flu.

As closed borders stop the main way the virus spreads here – through foreign visitors – and a national closure that stops what was still circulating, flu levels have fallen by an incredible 99 percent in 2020.

Since then, the virus has been virtually non-existent.

“The only flu cases we’ve had in the last two years have been in managed isolation,” said Dr. Nikki Turner, director of the Immunization Advisory Center (Imac).

With New Zealand ready to reopen to the world, health experts are concerned that two years of living in a flu-free environment would make our immune system vulnerable to the virus.

And for good reason: the flu traditionally infects about one in four kiwis each year, while causing about 500 deaths, making it still our only killer of infectious diseases.

“Our immune naivete will be a big problem, as most people don’t get the flu for two years, if not longer,” said Otago University virologist Dr. Gemma Geogan.

She noted that the outbreak of respiratory syncytial virus (RSV), which hit our children and hospitals last year – its true size was probably much larger than reported in 6,000 cases – after the Australian outbreak and the temporary resumption of transatlantic travel.

Although influenza continued to spread around the world, mostly still at a low level, health experts expected that cases would now arrive in our country – and several cases of influenza A have already been identified.

When can the flu really occur?

University of Otago virologist Dr. Gemma Johegan.  Photo / Supplied
University of Otago virologist Dr. Gemma Johegan. Photo / Supplied

“It’s a good question, because if the typical flu season lasts from about May to October with the peak of mid-winter, when we have less immunity, seasonality may not be such a significant factor,” Johegan said, adding that more people are inside. further exacerbate the spread.

“We’ve seen it in Australia with RSV, which is usually a winter virus, but it happened there in the summer – so maybe we can see an outbreak anytime our borders open.”

How many cases we could expect was unclear, but it didn’t take much more cases than seasonal volumes for hospitals already struggling with Covid-19 to come under pressure.

In 2018, for example, Auckland DHB was asked to send an appeal to the public after emergency workers saw 250 to 270 cases of influenza in adults a day, compared to the usual 200 for the winter.

This will not be the only unpleasant return

The discovery of New Zealand also meant the return of many other common viruses.

ESR public health doctor Dr Sarah Jeffries said that late last year there was an unusually high level of RSV infection in the Northern Hemisphere.

“This unusual RSV activity is similar to the experience in June in New Zealand last year, which was probably the result of reduced public immunity to RSV due to measures to combat Covid-19 in 2020 and increased population mobility, including fewer closures and some free quarantine trips, in 2021, ”she said.

“There is currently no vaccine to protect against RSV.”

Similarly, health experts are concerned about human metapneumovirus (HPV), enterovirus, adenovirus and highly contagious measles – not to mention the next wave of recurrent Omicron infections, as our immunity to this option is weakened.

Like the flu, these familiar troubles have also been shattered by our elimination strategy.

HPV levels fell by more than 92 percent, while even the tracked levels of rhinovirus, which causes colds, fell by three-quarters.

Despite widespread Omicron-like symptoms, experts expect to be able to track a number of viruses in our communities this year.

Dr Andrea McNeill, ESR’s technical director for epidemiology, said the monitoring is based on a range of data from society and hospitals, including calls to Healthline and a sample of a small number of cases referred to clinics by therapists.

While the pandemic has affected the number of flu cases, the response to Covid-19 has also spawned the development of a new and improved system for monitoring respiratory viruses.

“This system will be implemented in stages as soon as possible and will include the creation of a national repository for respiratory virus testing, which will allow us to monitor national indicators of respiratory virus testing,” McNeill said.

Normal weekly influenza monitoring will begin earlier than usual this year with the restoration of borders, and ESR is expected to begin reporting within a few weeks.

"The only cases of the flu we’ve had in the last two years have been in managed isolation," Says the director of the Immunization Advisory Center (Imac), Dr. Nikki Turner.  Photo / Mark Mitchell
“The only flu cases we’ve had in the last two years have been in managed isolation,” says Dr. Nikki Turner, director of the Immunization Advisory Center (Imac). Photo / Mark Mitchell

Otago University immunologist Dr. Diane Sika-Paatanu said monitoring of new coronavirus variants would remain important – especially if vaccinated travelers from outside Australia begin arriving in the country early next month.

“The spread in the community will be rapid if any new variants of Sars-CoV-2 can escape the protection provided by the currently available vaccines against Covid-19.”

Although Covid-19 has been the main focus for two years, she said childhood vaccinations have always been just as important – especially in the wake of a pandemic that disrupted immunization schedules.

“That means there is a potential risk of an outbreak of measles or whooping cough, for example.”

Vaccines are key, but Covid habits will also help us

In the Northern Hemisphere, researchers tracked the spread of two specific strains of influenza: most commonly strain A or H3N2, followed by strain B / Victoria.

The Southern Hemisphere vaccine – now available here and available free of charge to pregnant women, the elderly, Maori and Pacific people over 55, and people with certain diseases – has been targeted against four common strains and has been tuned for better protection against H3N2.

Jeffries said vaccination still provides the best protection against serious flu-like illnesses, as with Covid-19 measures – but hygiene measures are also important.

Turner noted that the countries of the Northern Hemisphere were free of severe flu outbreaks – something that could be partly due to pandemic practices.

“We’ve actually learned a lot from Covid, and people have really changed their behavior,” she said.

“Now more and more people stay at home when they are sick, they practice social distancing, and there is still mass disguise – all of which is of great importance and we can expect it to have an impact.

“So while we can’t predict what this flu season will look like, or say whether it will be serious or not, we need to be prepared for that.”

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