WHO Warns New Influenza Variant Linked to Severe Disease Surge, Symptoms to Watch Out For

The World Health Organization has warned that a newly emerging influenza variant is spreading rapidly across multiple regions, with health officials monitoring a rise in severe disease and hospitalisations as the flu season intensifies.

Speaking in Geneva, Dr Wenqing Zhang, head of global respiratory threats at the WHO, said influenza activity is surging alongside other respiratory viruses. This year, she noted, is marked by the rapid expansion of a new influenza AH3N2 variant known as subclade K, officially classified as J.2.4.1.

According to the United Nations report on the new influenza variant, the strain was first detected in Australia and New Zealand in August and has since been identified in more than 30 countries.

What Makes the New Flu Variant Different

Dr Zhang explained that influenza viruses constantly change, which is why flu vaccines are updated regularly. The current concern centres on the genetic evolution of subclade K, which shows a notable shift compared with earlier H3N2 strains.

While early WHO data does not yet show a clear rise in overall severity, scientists are closely tracking its spread due to growing reports of increased hospitalisations in some countries. The variant is not included in the most recent Northern Hemisphere vaccine formulation, as it emerged after vaccine production had already begun.

Despite this, Dr Zhang stressed that seasonal flu vaccines remain an essential defence. Early data from the United Kingdom suggests current vaccines still reduce the risk of severe illness and hospital admission, particularly among children.

Experts Track Severe Disease Trends

Independent experts have echoed the WHO's caution. Reporting by Scientific American on the new flu variant linked to severe disease shows that subclade K is now dominant in several countries, including the United States, the United Kingdom, Canada, and Japan.

In the U.S., health officials say the variant accounts for the vast majority of flu samples tested since late September. Hospitalisation rates remain broadly in line with previous years, although some regions, including Texas, have recorded increases among adults aged 65 and older.

Virologists say the mutations may slightly reduce vaccine effectiveness. However, they emphasise that vaccination continues to offer meaningful protection against severe disease and death.

Symptoms to Watch as Flu Season Peaks

Health authorities advise the public to remain alert to common flu symptoms, which include fever, chills, cough, sore throat, muscle aches, fatigue, and headaches. In more severe cases, symptoms can escalate to breathing difficulties, chest pain, or confusion, particularly in older adults and those with underlying health conditions.

Dr Zhang warned that the upcoming holiday season could drive further increases in transmission as travel and social gatherings intensify. She urged countries to strengthen surveillance, laboratory testing, and preparedness efforts to manage potential surges.

Vaccination Remains the Best Protection

Despite concerns around viral evolution, WHO officials remain clear that vaccination is still the most effective tool available. Globally, influenza causes an estimated one billion infections each year, with up to five million cases of severe illness and around 650,000 deaths linked to flu-related respiratory disease.

Early effectiveness data suggests vaccines reduce the risk of severe disease by around 75 per cent in children and roughly 35 per cent in adults. These figures reinforce public health guidance encouraging vaccination, especially for older adults, pregnant women, and people with chronic illnesses.

Global Surveillance Plays a Key Role

The WHO continues to rely on its Global Influenza Surveillance and Response System, which includes laboratories and influenza centres in more than 130 countries. This network helps track viral changes and informs future vaccine updates.

Dr. Zhang also highlighted the importance of international cooperation in monitoring influenza strains. She said global surveillance remains critical to detecting dangerous variants early and reducing loss of life.

As the flu season continues, health officials urge people to get vaccinated, stay home when unwell, and seek medical care promptly if symptoms worsen.