New coronavirus norms such as social distancing and proper hand-washing are probably to thank for the historically low influenza rates this year, but experts are unsure whether our good fortune will last
New coronavirus norms such as social distancing and proper hand-washing are probably to thank for the historically low influenza rates this year, but experts are unsure whether our good fortune will last.
At its peak in March this year, the FluTracking surveillance system reported that around 1.7% of its participants reported flu-like symptoms, but this had dropped to around 0.3% in its latest report for the week ending May 24.
This is an “historically low” rate, according to the report, which lists the five-year average for this time of year as around 2.5%.
More than 74,000 people participated in the latest report, signalling whether they had fever and cough, among other symptoms such as sore throat, runny nose, shortness of breath and a change in taste or smell.
Laboratory-confirmed flu cases reached a high of 7166 in February and dropped to 305 in April and only 138 in May.
There were more than 30,000 cases in May of last year alone, and an average of around 2,400 each May in the five years prior.
“I think it’s really clear that the measures that we’ve implemented to control COVID-19 are ones that will control a large number of infectious diseases, including all the respiratory viruses, including influenza,” Associate Professor Paul Griffin, an infectious diseases physician and microbiologist at the University of Queensland, said.
This could have major flow-on effects.
“You will see fewer deaths attributable to flu this year, for example,” Professor Griffin said. But there were also a lot of consequences of flu that were hard to measure, such as GP presentations, days off work, admissions to hospital and exacerbations of comorbidities which had “a huge impact”.
We should be seeing a drop in other respiratory viruses, such as RSV, and potentially gastroenteritis-causing viruses too, he added.
“It’s been really fascinating to see what’s happened with the flu because it highlights that possibly some of the interventions we’re doing now, obviously not at the same scale, could be things that we could continue moving forward in an effort to reduce the burden of influenza,” he added.
“I think we became a bit complacent with the flu,” he said.
In addition to proper hand-washing, Professor Griffin hopes that one lesson to carry into our post-pandemic society was for people to stay home when they were unwell, rather than coming into work and spreading the infection.
But humans tend to have short memories and history tells us that such vigilance may fade as the threat of COVID-19 lessens. The healthcare system had great pandemic plans and stockpiles of PPE and drugs in response to the 2009 influenza pandemic, only to be eroded over the years.
“It’s a real risk that we’ll do this stuff really well for a few years and then other priorities will emerge and we’ll become unprepared once again, probably just in time for the next one,” Professor Griffin said.
A significant amount of influenza is imported from overseas, particularly in the off seasons. So keeping our borders closed would probably continue to have a big impact this season, he added.
Nevertheless, Flinders University professor and flu vaccine developer Nikolai Petrovsky, noted that flu seasons varied wildly from year to year, and one explanation for the low rates seen so far was that we are in a mild flu season, or a late one.
“The hardcore flu season is quite late in the year,” he said. “It typically peaks in August- September, so we just started the flu season.”
While there was less flu around than a normal year at this time, all of the usual respiratory viruses were being found on COVID-19 swabs and people were still being hospitalised for flu, he said.
“So we shouldn’t be complacent, because flu can come very late, and then hit you really hard,” Professor Petrovsky said.
So far, more than 7.3 million flu vaccines have been administered this year, up from 4.5 million in the same period last year and more than twice the 3.5 million doses in the same period in 2018, Health Minister Greg Hunt said on 27 May.