Is it normal to have seven summer flu deaths?

Saturday, 17 February 2024

An influenza outbreak has seen six die at a Whitianga rest home while another person has also died from flu in Wellington this year
Is the number of deaths unusual for this time of year?

In late January, residents and staff at a coastal Whitianga aged care home started developing flu-like symptoms of fever, sore throats, coughs, and headaches.

In the space of 12 days, between January 28 and February 8, six elderly residents aged 80 to 98 died.

The outbreak began on January 26, when a resident was hopitalised with influenza A, Anita Hawthorneof facility owner Oceania Healthcare told Stuff.

Over time, 18 residents and 10 team members had symptoms.

Te Whatu Ora (Health New Zealand) officially closed the outbreak on February 9, based on no further spread.

Meanwhile, there was another outbreak in an aged care home this year in Wellington.

Dr Susan Jack, national clinical director at the National Public Health Service, told Stuff that in the Wellington case there were 18 cases and one death.

Jack said they were confident the situation was appropriately managed and that there was no further spread.

These kinds of outbreaks were a “timely reminder that influenza can occur outside of winter, and that the elderly are vulnerable to both Covid and influenza,” she said.

So how unusual is a flu outbreak at this time of year?

Virologist Dr Sue Huang, principal investigator at the Institute of Environmental Science and Research, said it was “rare” for flu outbreaks to occur in rest homes in summer, but it’s not “unheard of”.

Flu hits its peak in the winter months, with most cases in Aotearoa occurring between May and October. But it never goes away altogether.

Influenza circulates at a very low level in summertime, usually from travellers coming to New Zealand from northern hemisphere countries where the flu is circulating, virologist at the Institute of Environmental Science and Research (ESR), Dr Sue Huang said.

Occasionally, influenza outbreaks occur in New Zealand’s summer — but these tend to occur in younger, dynamic groups such as university students and fruit pickers, Huang said.

While flu outbreaks in rest homes in summer were “rare”, they were not unheard of, she said.

Why was it so deadly?

Weekly virology data shows that influenza A (H3N2) is the predominant subtype at the moment.

It isn’t yet clear what type of flu virus caused illness among the Whitianga care centre, but Huang said H3N2 hits elderly people particularly hard, especially those with underlying health conditions.

Crown research agency ESR was still in the process of receiving samples to characterise the virus.

Flu is quite contagious and older people and the elderly are among those most vulnerable, especially if in a group setting, Huang said.

The risk of flu-related death increases with age, chronic conditions or increasing levels of frailty.

The risk of flu-related hospitalisation is also greater for older people, compared to healthy adults aged under 65.

Anita Hawthorne, group general manager sales and services at Oceania said in a written statement that their “deepest sympathies are with those families who have lost a loved one through the influenza virus”.

Epidemiologist Professor Michael Baker said while it was “surprising” to see an outbreak at this time of year and once flu gets into a rest home it can be “quite devastating”.

This is in large part due to the vulnerability and frailty of people living in these environments, and the fact they’re living in close quarters, he said.

A review of 49 influenza outbreaks in long-term elderly care facilities across 19 countries, published in 2010, found the median attack rate (the percentage of people who became infected) was 33%.

The median hospital admission rate was 14% for influenza, and there was a median case fatality rate (of those who got influenza, the proportion who died) of 6.5%.

Baker said the Whitianga outbreak emphasised the importance of keeping influenza and respiratory illnesses out of environments such as aged care facilities altogether, given the vulnerability of the people who live in them.

The World Health Organisation (WHO) reports H3N2 predominates in many countries, and is evolving with new strains.

One piece of good news was that the Southern Hemisphere vaccine to be used this year will cover these new strains, Huang said.

Do people normally die of flu over summer?

Around 500 people die from the flu each year, it’s reported.

The most recent official mortality data we have available by month is from 2019 ‒ this is because of the time it takes to collate coronial data, as the recorded cause of death needs to be as accurate as possible.

2019 was the worst year for registered influenza deaths since 1970 — more than 50% higher than any year since 1985, national director of the National Public Health Service, Dr Nick Chamberlain told Stuff.

In 2019, there were 201 influenza deaths registered, most of which occurred in July (61 deaths), Chamberlain said.

Of all influenza deaths registered between 2000 and 2019, most were in July (226) followed by August (204).

Very few were in January (two) and February (five), the data provided by Te Whatu Ora shows.

What’s the flu doing at the moment?

The number of flu viruses reported in 2024 to date are comparable to what was seen at the same time last year, Huang said.

The laboratory-based surveillance for influenza is carried out year-round by the virus laboratory network at ESR and six hospital laboratories in Auckland (home to two labs), Waikato, Wellington, Christchurch and Dunedin.

It shows there have been 215 influenza respiratory viruses reported in the first six weeks of the year.

Of these, 188 were influenza A ‒ 15 were typed as H1N1 (colloquially known as swine flu, which was one of the main strains in Aotearoa last year), and 33 were H3N2.

In comparison, there were 268 influenza viruses reported in the first six weeks of 2023.

Jack said it is important people do not visit elderly people if you are sick, even if your RAT was negative. Visiting elderly people when you are sick should only be done if the situation is critical and cannot be delayed until you are well.

In this situation, you should wear a mask and seek advice from the facility.

You should also wear a mask (even if you don’t have symptoms) – particularly if you have had recent contact with someone with Covid or respiratory symptoms, she said.

Many people with the flu do not have symptoms but can still spread it to others, Jack said.