Is COVID Back? Mystery Flu Outbreak in Asia Sparks Panic, Experts Reveal the Disturbing Truth

The world breathed a sigh of relief as the worst of the COVID-19 pandemic seemed to fade, but a sudden, unidentified 'flu' circulating in parts of Asia has put everyone back on edge.

With memories of lockdowns and global health crises still fresh, is this new wave a sign that COVID is making a dramatic return, or is something else entirely behind the rising panic? Health professionals are now stepping in to clarify the situation and disclose what's truly going on.

The sudden rise in influenza infections across numerous Asian nations has prompted warnings from some medical professionals: being more susceptible to illness year-round could become the standard expectation.

Japan on High Alert: The Flu Season That Broke the Calendar

On 3 October, Japanese health officials announced a national flu epidemic after an unusual wave of cases struck five weeks ahead of the typical flu season. This marks the second-earliest flu outbreak the country has recorded in the past two decades.

Between 22nd and 28th September, the number of people treated for influenza in Japan surpassed four thousand. According to the nation's Ministry of Health, this figure translates to an average of 1.04 patients per monitored medical centre. This rate officially exceeded the necessary level to declare an epidemic.

The situation worsened quickly: the number of patients receiving treatment for influenza had since risen to over 6,000 people between 29th September and 5th October. This surge translated to 1.56 patients per monitored institution, representing more than twice the figure of 0.77 recorded for the exact same period the previous year.

The impact on daily life was immediately noticeable: from 22nd September to 3rd October, 135 schools and childcare facilities across the nation were forced to close their doors — a frequency three times higher than during the corresponding period last year. Out of Japan's 47 regions, 28 prefectures documented a rise in flu cases, with Okinawa recording the highest patient count per medical establishment.

The Flu Spreads Across the Continent

However, this phenomenon isn't limited to Japan. Influenza cases have also spiked in recent weeks across other nations on the continent, including Singapore, Thailand, and India. The latter country, in particular, has experienced a significant spread of the H3N2 virus across its north.

The seasonal H3N2 strain is a descendant of the virus responsible for the 1968 Hong Kong flu pandemic, which itself was a combination of both human and avian influenza viruses. This information was shared with DW News by Dr Martin Beer, vice president of Germany's Federal Institute for Animal Health, the Friedrich Loeffler Institut.

The flu describes an infection triggered by any of the four types of influenza viruses: A, B, C, and D. Of these, influenza A and B are responsible for the typical seasonal outbreaks seen in people.

While the flu shares many symptoms with the common cold, the difference lies in the cause: the common cold is the result of various other viruses, such as rhinoviruses, according to the US Centers for Disease Control and Prevention (CDC).

This overall increase in flu cases across Asia, alongside the earlier outbreaks observed in Europe this year, has led some health professionals to issue a warning: influenza may be adapting to circulate faster or arrive earlier than usual in particular geographical areas.

Commenting on the Japanese epidemic, Yoko Tsukamoto, a professor at the Health Sciences University of Hokkaido, told the South China Morning Post: 'The flu season has started really early this year, but in the changing global environment this might become a more common scenario.'

Further raising concerns, Nicola Lewis, director of the Worldwide Influenza Centre at the Francis Crick Institute in London, issued a warning last year that the next global pandemic could potentially be flu-driven.

Lewis stated, 'I think the chances that disease X will be an influenza virus are probably greater than for any other known pathogen group that I can think of.' This term, Disease X, refers to a hypothetical new or currently unknown illness that could cause a worldwide health crisis.

Tropical Paradox: How Weather and Human Habits Fuel the Flu

Singapore has recently observed a climb in acute respiratory infections, predominantly rhinoviruses and influenza, according to the Ministry of Health's surveillance figures. Flu infections rose sharply last month, with Dr Zhang Qi noting a 'sustained and clear surge', while DoctorAnywhere documented an increase of up to 40%. Although influenza typically sees its peak activity between December–March and May–August, the Communicable Diseases Agency has yet to find any indication of greater severity.

Dr. Kimberly Fornace from NUS explained to TIME that while the flu's seasonal nature is well-established in colder regions (as people spend more time inside), the patterns in tropical climates are less clear. She added that the wetter months, which also encourage indoor crowding, might create similar conditions. Both Singapore's recent inter-monsoon thunderstorms and the concurrent flu surge in Thailand coincided with significant rainfall. Thailand's surge saw over 30,000 new cases in early September, contributing to a total of 555,000 cases and 59 fatalities.

A 2024 study in Singapore connected climate change — including factors like heatwaves, rainfall, and cyclones — to increased transmission of vector-borne and waterborne diseases. However, this link was not specifically established for influenza.

Separately, Kai Kupferschmidt of Science magazine proposed that global warming might make flu less severe but more continuous throughout the year. Dr Fornace further commented that shifts in climate impact disease spillover, transmission, and human habits. Additionally, Dr Sophie Dennis of the WHO and Prof. Dale Fisher from NUS pointed out that crowding indoors during bouts of extreme weather could accelerate the spread of influenza across all climates.

How Flu Strains Threaten to Bypass Immunity

Dr Paul Tambyah, former president of the Asia Pacific Society of Clinical Microbiology and Infection, explained to TIME that new virus strains are probably behind the increase in flu cases. The WHO's update for the 2026 Southern Hemisphere vaccine included two new strains — A/Missouri/11/2025 (H1N1)pdm09-like and A/Singapore/GP20238/2024 (H3N2)-like — signalling drifted variants that could circumvent the protection offered by previous immunity. 'Hence the rise in flu cases in many parts of the world', Tambyah added.

Meanwhile, officials in Japan also cited the increase in global travel and tourism as additional factors contributing to the virus spreading and adapting, according to the SCMP. While Tambyah acknowledged that the evolution of influenza is a constant process, he stressed there is 'no evidence' that the rate is currently speeding up.

Nonetheless, he issued a cautionary statement about the possibility of new strains — beyond H1, H3, or Flu B — such as H5, H7, or H9 emerging from animals. These could potentially spark a pandemic, much like the 1957 H2N2 'Asian Flu', which claimed over 1.1 million lives worldwide (CDC).

Highly pathogenic bird flu's rapid evolution, including recent detection in US cattle, raises concern; infections in mammals make human-transmissible mutations more likely, notes Lewis, WHO's Worldwide Influenza Centre director. Flu viruses can also undergo reassortment when multiple strains infect a host, producing novel viruses — a process especially likely in pigs.

Lewis added, 'We have never seen this kind of situation with a highly pathogenic H5 virus before. I certainly think that if you'd asked me in 2019, this would not have been the picture I would have conjured up in my mind about what bird flu could do.'

Vaccination: Your Crucial Defence Against the Evolving Flu

Health experts are strongly advising everyone to stay up to date with the local influenza vaccines. Tambyah stated there's no actual "immunity deficit" resulting from the COVID-19 pandemic, pointing out that death rates from respiratory illnesses have stayed stable. In fact, the pandemic may have even boosted awareness of preventive measures like mask-wearing and careful hand hygiene.

Concerns remain, however, due to persistent global vaccine reluctance, particularly within high-income nations like Singapore and Japan. Vaccination can significantly lessen illness and complications, meaning that employers and workplaces should actively discourage staff from attending work while unwell.

Ramanan Laxminarayan of One Health Trust underscored that vaccines are particularly essential for the elderly and other high-risk individuals, but their effectiveness depends on precise strain prediction. He added that the ideal long-term fix would be a universal flu vaccine — one that works against all strains and lasts for a decade — but that solution is not yet available.

Originally published on IBTimes UK