New Hong Kong flu subtype detected across 30 countries, WHO reports

Experts from the World Health Organisation (WHO) are tracking the rapid international spread of the influenza A(H3N2) virus, commonly known as Hong Kong flu, which has now been detected in 30 countries worldwide.

The update was provided by Wenqing Zhang, head of the Global Respiratory Threats unit within the WHO’s Department of Epidemic and Pandemic Preparedness.

Zhang said that with the start of the winter season in the Northern Hemisphere, health authorities are seeing a rise in influenza cases alongside other respiratory viruses. At the same time, she stressed that overall global influenza activity this season remains within the expected range. She noted that the organisation is closely monitoring the emergence and fast spread of a new A(H3N2) subtype known as J.2.4.1.

According to Zhang, this subtype was first identified in August in Australia and New Zealand. Since then, it has been detected in more than 30 countries across all regions of the world, with the sole exception of South America. She made these remarks during a briefing in Geneva.

The WHO expert emphasised that current epidemiological data do not indicate an increase in the severity of illness associated with the new variant. Preliminary findings suggest that existing seasonal influenza vaccines continue to provide protection against severe disease and help reduce the risk of hospitalisation.

Zhang also pointed out that influenza is circulating alongside several other respiratory viruses, including respiratory syncytial virus, coronavirus, and rhinoviruses. In some countries, health care systems are coming under additional pressure not only because of rising hospital admissions linked to respiratory infections, but also due to the seasonal increase in other viral diseases, such as norovirus.

According to information published on the WHO’s website, Hong Kong flu belongs to the group of acute respiratory infections caused by influenza viruses that circulate globally throughout the year.

There are four types of influenza viruses: A, B, C, and D. Influenza A and B are responsible for seasonal epidemics.

The WHO notes that influenza spreads easily through airborne droplets. While most infected people recover within about a week without medical treatment, the disease can lead to serious complications, which is why the organisation continues to recommend vaccination.