Australia is grappling with the “yo-yo flu”, where cold symptoms continually return, as a sharp rise in respiratory infections has been driven by an early flu season, continuing cases of COVID-19 and the circulation of nasty viruses.
Sydney pharmacist Sylvia Thai said she and her family had been sick intermittently for the past several months, and believed it was a byproduct of low natural immunity.
“We’ve been constantly sick, and it’s been going around in a cycle, we keep giving it to each other,” she said.
Working in a pharmacy, Thai is used to being exposed to illness, but this year is different after two-and-a-half years of social distancing and mask-wearing.
“Our immune systems haven’t had a chance to grow and all of a sudden, the world is normal and all the germs are coming out, and our bodies don’t know what to do,” she said.
Caroline Diamantis, the owner of Balmain Community Pharmacy in Sydney’s inner west, said about 10 customers a day were coming into the pharmacy requesting leave certificates and cold and flu medication, many of them coming back every few weeks.
“It seems like a bit of a crisis, and it’s quite worrisome,” she said but added there was plenty of stock of over-the-counter medications.
The Royal Australian College of General Practitioners vice president Bruce Willett said there were three factors potentially driving sickness rates: a range of viruses, a lack of natural immunity, and potentially long COVID-19.
“We’ve just had a lot of really nasty bugs circulating at once,” he said.
So far this year, there have been nearly 10,000 more cases of respiratory syncytial virus (RSV) compared with 2022, and an average of 714 COVID-19 cases were reported per day across Australia in the past week.
Australia’s flu season started early in March instead of April or May, and there have been nearly 250,000 lab-confirmed influenza cases in the year to date.
Willett said Australians would also have limited natural immunity after two years of staying indoors, increasing their susceptibility to infections and secondary infections – though this was likely to be the final year of low immunity levels.
“If people catch COVID, a cold or the flu they can get secondary infections like sinusitis or ear infections while their immune system is weak,” he said.
“People should be mindful to get some help if they’re getting progressively worse.”
Long COVID may also play a role, but Willett said there was limited data to support this hypothesis. The Burnet Institute estimates that 5 to 10 per cent of people in Australia have persisting symptoms for three months, or twelve weeks, after an initial COVID-19 infection.
Australian Centre for Disease Preparedness immunologist Dr Daniel Layton said that while Australia was in the middle of a “bad” cold and flu season, these were common occurrences.
“The newly emerging term ‘yo-yo flu’ refers to people getting sick consecutively week after week, maybe feeling like they’re getting better and then getting sick again, but it is certainly not a new thing,” he said.
“We haven’t seen any evidence that there’s a new virus associated with it.”
Layton said different viruses might cause lingering symptoms such as coughs even when an infection has passed, while a rise in the number of people travelling more frequently might have led to the spreading of viruses.
Infections can be prevented with handwashing, social distancing, keeping a healthy diet, exercise and sleep schedule, and getting the flu vaccine every year.
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