The absence of influenza in the community has been described as ‘amazing’, but it is also making planning for next year difficult.
Laboratory-confirmed influenza deaths recorded by the National Notifiable Disease Surveillance System over the past five years.
Influenza experts never thought they would see the scenario currently unfolding in Australia.
In a month when flu cases are normally rising to a peak, no deaths have been reported anywhere in the country for the year to date. And according to the Australian Bureau of Statistics, the last Australian death officially attributed to influenza was recorded in July 2020.
Professor Ian Barr is the Deputy Director of the World Health Organisation Collaborating Centre for Reference and Research on Influenza at the Doherty Institute. He is frank when asked if he ever imagined the current situation; just 435 cases notified to the Australian Influenza Surveillance Report so far this year and no hospital admissions.
‘No. It’s amazing. Never,’ he told newsGP.
While there have been cases of influenza in quarantine, almost none have been in the community either in Australia or New Zealand. Data from the Australia Influenza Surveillance Report suggests the historically low levels observed last year have declined further still in 2021, notwithstanding a rise between January and May.
For context, there were 21,005 notifications of laboratory-confirmed influenza by this time in 2020 and 36 deaths. In 2019, there had been 214,377 and 486 deaths.
Professor Barr says the absence of influenza is a positive, although he also points to a number of other respiratory illnesses – beyond the rising number of COVID-19 cases – still present in the community.
‘I think fighting one virus at a time is quite enough for the general public,’ he said.
‘I don’t think we should get too complacent. There are other viruses circulating and depending on which state you’re in, those viruses are circulating at different levels.
‘We have seen a resurgence of other viruses already – RSV [respiratory syncytial virus] is a very good example of that.’
Dr Kerry Hancock, Chair of RACGP Specific Interests Respiratory Medicine, reports a similar trend – although qualifies that by saying she does not believe there is a higher rate of RSV than before the pandemic.
‘Because we’re swabbing for COVID, we’re actually seeing what those viruses are: adenovirus, parainfluenza, RSV, rhinovirus,’ Dr Hancock told newsGP.
‘This time last year, we weren’t seeing as much as there was a lot more social distancing – and a lot of the young children were kept home from childcare.’
The negligible presence of influenza in Australia is likely to continue for some time to come, Professor Barr believes, with the re-opening of international borders the biggest factor.
‘Things will start to happen pretty quickly as borders are relaxed,’ he said. ‘It will take a while for the numbers to build up to feed into the surveillance systems.
‘I would think within 12–18 months we’ll have a good idea of where the human seasonal influenza viruses are hitting.’
From a biological point of view, Professor Barr describes it as a ‘very interesting’ moment for those tracking influenza, with the unprecedented situation making it hard to map out what happens next.
‘We’re a little unsure about which way the virus might go; whether or not we might lose some of these influenza viruses, or whether something new might emerge or go back and reset where we were,’ he said.
‘What we’re seeing makes it difficult for updating vaccines … if you look at it from the virus’s point of view, it’s never been under these sort of pressures before.
‘It does make our predictions even more difficult than normal.’
As well as reducing the presence of the virus in the country for the time being, the health measures adopted during the pandemic could allow for greater scope to tackle influenza in the future, Professor Barr believes.
With schools having to shut down due to COVID-19 concerns, and mask wearing now prevalent, he hopes the community will be more likely to use such preventive measures if influenza is circulating.
‘I think some of those things will certainly be introduced,’ Professor Barr said. ‘Will they stop influenza completely? It’s very unlikely. Can they impact on the severity of the seasons? I would like to think so.’
There are concerns, however, that the virus’s absence now could be the precursor to a significant outbreak when it returns.
‘There is a real possibility that we will have a big rebound in the next one or two years – if not 2022 it may well be 2023,’ he said.
‘With lower levels of vaccination and virus circulating, the herd immunity levels will be going down by the month. If we don’t see any influenza for another two years, then we will have a highly susceptible population and that usually means a big year for influenza.’
While Professor Barr hopes combining COVID-19 vaccine boosters with influenza vaccination may be possible, he predicts it may be hard to get the program back on track.
‘Once you disrupt people’s regular routines, inevitably, it’s more difficult to get them back again in the future,’ he said.
It is a concern the Dr Hancock shares.
‘Because there has been no influenza around, there’s not been the uptake in the vaccination,’ she said.
‘It does concern me that people have got complacent about influenza vaccination. Not so much the elderly, who are in the habit, but even [they] have not been as enthusiastic.
‘When the quarantining stops, do we risk having a horrendous influenza season?’
Dr Hancock is also worried that uptake may only increase if influenza outbreaks are seen again, in a similar pattern to the current surge in interest in COVID-19 vaccination as case numbers increase.
‘The behaviour is the same. It’s very frustrating, it’s not understanding what vaccination is about,’ Dr Hancock said. ‘You don’t wait until you are exposed to it.’
