The worsening flu season in Australia has provoked fears among UK scientists that the country will follow suit this winter, leading to mass infections and hospitalisations among all age groups.
Australia is bracing for its worst flu seasons in five years, after Covid restrictions suppressed the circulation of the influenza virus in 2020 and 2021.
Almost 40,000 cases have been reported in the country since the beginning of the year, 26,000 of which have come in the second and third week of May. Hospitalisations are doubling every week in the state of Queensland, while nationwide rates are particularly high among young people.
The Australian Medical Association (AMA) has warned of a looming “disaster,” with scientists in the UK fearful that similar scenes could be repeated once winter sets in.
Julian Tang, a professor of respiratory sciences at the University of Leicester, said Britain does not always follow the trend seen in the southern hemisphere.
However, this year, he added, “I think we will see more flu as Covid-19 restrictions are lifted (enhanced social mixing and international travel), together with reduced cross-protective immunity to any recently circulating flu strains because of restrictions.”
Prof Tang said emerging data suggests that the global incidence of influenza is returning to its pre-Covid levels. Different strains of the virus are re-circulating in different parts of the world, some of which are more transmissible and deadly than others.
“In fact, there may be some overshoot because of that lack of previous exposure/immunity during the pandemic years – so we may experience a worse flu season in the coming winter than those that we experienced pre-Covid,” Prof Tang added.
“This may also apply to other seasonal respiratory viruses, that have all been suppressed significantly due to Covid restrictions.”
Professor Deenan Pillay, a virologist at University College London, also said he believed that the UK “will follow the southern hemisphere” this year.
The World Health Organisation (WHO) convenes technical consultations twice a year, in February and September, to recommend which viruses to include in the seasonal flu vaccines for the northern and southern hemispheres.
Health authorities in Australia have said it is “too early” to determine the effectiveness of the flu vaccine currently being rolled out in the southern hemisphere. The country is experiencing large outbreaks of two co-circulating influenza strains, H1 and H3.
The Joint Committee on Vaccination and Immunisation (JCVI) has already begun discussions for the UK’s flu vaccination programme, with operational guidance for the coming season set to be outlined after the forming meeting in June.
The vaccine watchdog will consider dosage and eligibility based on the experience of the southern hemisphere, along with other epidemiological reports and research.
Dr Maggie Wearmouth, a former JCVI member, said she was concerned by the situation in Australia, adding that “we always take the patterns of flu in other hemispheres very seriously in planning for forthcoming winter flu programmes”.
John McCauley, director of the Worldwide Influenza Centre at the Francis Crick Institute, who helps decide vaccine recommendations at the WHO’s bi-annual meetings, said the increase in Australia “has indeed been very sudden, and this might be indicative of waning immunity”.
He noted that New Zealand has yet to see much flu, “but it looks like South Africa’s season has started”.
Some countries in Europe, such as France, Luxembourg and the Netherlands, have experienced a late rise in cases toward the end of their flu seasons, yet this hasn’t been seen in the likes of the UK or Russia, Dr McCauley added.
“It’s been unusual in parts of Europe, and very different from China,” where there has been “a huge predominance of influenza B activity”.
Dr McCauley said there was much uncertainty ahead but warned that “we need to watch everywhere”.
